Jeremy Grantham on The Diary Of A CEO: The AI Bubble, Bitcoin, SpaceX and the Case for Getting Out of US Stocks

In this episode of The Diary Of A CEO with Steven Bartlett, billionaire investor Jeremy Grantham argues that artificial intelligence is not just another technology trend, but the center of what he calls possibly the biggest investment bubble in American history. He warns against US stocks, dismisses crypto, questions the fantasy valuations around SpaceX, talks about declining fertility, and ends up making a much wider argument about social trust, inequality, toxicity and where he would — or would not — want to live.

The official Apple Podcasts listing describes the episode as a conversation with the man who predicted the dot-com crash and the 2007 housing collapse, with Grantham explaining why he thinks the AI bubble will burst, why house prices may need to fall, and why everyday chemicals may affect fertility. The listing also identifies Grantham as the co-founder of GMO, long-term investment strategist, chairman of the Grantham Foundation for the Preservation of the Environment, and co-author of The Making of a Permabear.

This review uses the supplied transcript as the primary episode source.

Episode at a glance

The YouTube search result for the episode listed it at roughly 2.6 million views around the time of review, which helps explain why this episode is already becoming one of the more visible finance-and-AI podcast conversations of the week.

What happens in the episode?

The episode begins with the kind of clipped, high-stakes preview that The Diary Of A CEO has made into a signature format. Bartlett throws out direct questions: What should ordinary people do with their salary? Should they own the S&P 500? What about crypto? What about SpaceX? Grantham answers with the severity of a man who has spent decades watching optimism turn into financial wreckage.

His answer to US stocks is blunt: he does not want them. His answer to the S&P 500 is also no. His answer to crypto is even colder. He calls it unnecessary, volatile and useful mainly for speculation and hidden money movement. On Bitcoin, he says that in the distant future he believes it goes to zero.

Then the conversation widens. Grantham is not simply saying that AI is overhyped. In fact, one of the most important nuances in the episode is that he thinks AI is genuinely huge. His warning is not “AI is fake.” His warning is closer to: the greater the technology, the more dangerous the investment mania can become.

He compares AI to railroads and the internet. The railroads changed the world, but railroad investors could still lose fortunes. The internet transformed commerce, communication and media, but Amazon still fell massively during the dot-com crash before later becoming one of the great winners. Grantham’s argument is that revolutionary technology and disastrous investment returns can exist in the same story.

That is the core tension of the episode. Bartlett keeps bringing the conversation back to practical consequences: What does this mean for the average person? What should founders do? What should investors do? What happens to jobs? What happens if the market crashes? Grantham answers at several levels. There is the portfolio level: diversify, consider non-US equities, hold bonds, hold some cash, maybe keep a small allocation to precious metals. There is the founder level: raise capital while money is still available, because when the tide turns, funding can disappear. There is the civilizational level: inequality, fertility decline, toxic chemicals and a weakening social contract may matter as much as stock prices.

The result is a strange but compelling episode. It starts as an investment interview and gradually becomes a conversation about whether modern society has built too much on optimism, leverage, extraction and short-term thinking.

The biggest talking points from the episode

Jeremy Grantham says AI can be revolutionary and still become a bubble

One of the strongest parts of the interview is Grantham’s refusal to reduce the AI debate to simple hype versus skepticism. He does not dismiss AI as a gimmick. He places it among the major technological shifts of recent centuries.

That makes his warning sharper. His view is that bubbles often form around important ideas, not worthless ones. The more obvious the opportunity looks, the more capital rushes in. The more capital rushes in, the more likely the market overshoots. That is how a life-changing technology can become a wealth-destroying investment cycle.

This is a useful corrective to a common mistake in public debates about AI. Many people assume that if AI is real, then every AI-linked valuation is justified. Grantham’s historical framing says otherwise. Railroads were real. The internet was real. The Japanese corporate boom was real. The problem was not that the underlying stories were meaningless; the problem was price, timing and mass psychology.

A recent MoneyWeek interview with Grantham made a similar point, reporting that he sees AI firms commanding extreme valuations and compares current enthusiasm to past bubbles, while still acknowledging AI’s transformative potential.

The “don’t own US stocks” moment is built for controversy

The most viral investment line in the episode is Grantham’s warning against US stocks. He does not merely say “be cautious.” He says that investors should consider owning broad non-US equity exposure instead.

That is jarring because it runs against the most common retail investing message of the last decade: buy the S&P 500, stay diversified, do not overthink it. Grantham’s argument is that the US market has had such a powerful run that people now assume its dominance is permanent. He thinks that assumption is exactly what usually appears late in a cycle.

The episode would have benefited from a clearer breakdown of the risks of following such a view. For example, moving away from US equities can underperform badly if the US continues to lead. Currency exposure matters. Taxes matter. Individual time horizons matter. Bartlett does ask practical questions, but the show’s dramatic framing sometimes makes Grantham’s views sound more like instructions than a thesis.

Still, as podcast material, this is strong. It gives listeners something concrete to debate: Is the S&P 500 still the default answer, or has it become too crowded?

Wall Street incentives become one of the episode’s real villains

Grantham’s critique of investment advisors is one of the most pointed sections of the episode. His claim is that major investment firms are structurally unlikely to tell clients to exit an overvalued market because doing so is bad business.

This is one of the places where the episode becomes less about charts and more about incentives. Grantham argues that large firms are rewarded for keeping clients invested, keeping assets under management and avoiding lonely contrarian calls. If everyone is wrong together, careers survive. If one person is early and alone, the market can punish them professionally long before history vindicates them.

Bartlett is effective here because he translates the argument into plain language. The question becomes: if the people paid to guide investors have business reasons not to sound the alarm, what is the ordinary person supposed to do?

Grantham’s answer is not comforting: look at the data yourself, understand bubbles, and do not expect help to arrive at the top.

The SpaceX exchange gives the episode its sharpest tension

The SpaceX section is the most entertaining clash in the episode because Bartlett is personally invested. Grantham calls the SpaceX story wildly speculative, especially where future value is tied to asteroid mining, Mars ambitions and AI infrastructure. Bartlett pushes back with the obvious counterexample: Elon Musk has already made impossible-looking things look possible.

This is where the interview briefly becomes less predictable. Bartlett is not simply nodding along. He brings up Tesla, Starship, reusable rockets, Neuralink and autonomous driving. Grantham concedes Musk’s extraordinary ability to create magic, but argues that this does not automatically justify any valuation at any price.

That distinction matters. Grantham is not saying Musk has achieved nothing. He is saying technological theater, founder charisma and speculative valuation can reinforce each other until investors stop asking what the business is actually worth.

The tension works because neither side is completely absurd. Bartlett is right that Musk has a record of making skeptics look too cautious. Grantham is right that great engineering does not suspend valuation.

Bitcoin and crypto get almost no sympathy

Grantham’s view of crypto is simple: he does not own it, has not owned it, does not intend to own it, and would not advise anyone to buy it.

The exchange is memorable because it is so unqualified. In many finance podcasts, crypto is treated as a complex asset class with competing interpretations: digital gold, speculative technology, alternative monetary system, risk asset, fraud playground, financial revolution. Grantham strips away that debate and calls it unnecessary.

For listeners who hold Bitcoin or follow crypto closely, this section may feel underdeveloped. Bartlett asks the right question — why? — but the conversation does not deeply engage with the strongest pro-Bitcoin arguments, such as censorship resistance, fixed supply, self-custody or the role of monetary distrust. Grantham’s criticism is clear, but not especially detailed.

As a podcast moment, though, it is highly searchable. “Jeremy Grantham Bitcoin zero” is exactly the kind of phrase that travels.

The AI risk discussion moves from markets to human survival

The episode’s AI conversation does not stay confined to stock prices. Grantham and Bartlett discuss whether AI systems can be made benevolent, whether they might become judgmental, and whether competition between major AI companies makes safety harder.

This part of the episode is less financially precise but more culturally revealing. Bartlett brings up his own experiences with AI assistants becoming more moralizing or restrictive. Grantham connects that to the larger alignment problem: what does it mean to build a system that wants good for humans, and who defines good?

The conversation touches familiar AI-risk examples, including the “paperclip” thought experiment, where a poorly specified goal leads a powerful system to destructive behavior. The Stanford-led foundation model report has similarly emphasized that large AI systems carry both broad opportunities and risks, including social, ethical, economic and governance challenges.

This section will work for listeners who like big speculative questions. It may frustrate listeners who want a tighter distinction between current AI products, frontier AI safety debates and investment valuations.

The fertility section turns the episode into something much broader

Around the final third, the episode shifts from investing into fertility, toxins, pesticides, plastics and sperm count decline. This could have felt like a derailment, but it actually fits Grantham’s worldview. He is interested in long-term systems that are quietly deteriorating while short-term markets look cheerful.

The scientific background is complicated. A 2023 meta-analysis led by Hagai Levine reported continuing declines in sperm count and suggested that the decline has accelerated in the 21st century, while calling for urgent research into causes. A 2024 study found microplastics in all tested human and dog testes, though causal links to human fertility outcomes remain an area needing further research. Harvard researchers have also reported associations between higher pesticide-residue fruit and vegetable intake and lower sperm count among men at a fertility clinic.

The episode uses these findings dramatically. That makes the material compelling, but also increases the need for careful interpretation. Association is not always causation. Human fertility is affected by age, lifestyle, heat exposure, obesity, smoking, endocrine-disrupting chemicals, timing, medical conditions and social choices. Grantham’s emphasis on toxicity is important, but the episode could have done more to separate established evidence from extrapolation.

Inequality and maternal mortality become the moral center

Late in the conversation, Grantham argues that the US is fraying because inequality has weakened the social contract. He brings up housing, healthcare, wealth concentration and maternal mortality as signs of a society that creates spectacular wealth for some while failing basic tests for others.

This is one of the episode’s most powerful shifts. What began as “should I sell stocks?” becomes “what does a civilized country owe mothers, children and ordinary families?”

The broader data supports at least part of Grantham’s concern. The Commonwealth Fund reported that the US maternal mortality rate remains far higher than rates in other high-income countries, with persistent racial inequities. OECD data also shows that several countries, including Norway and Denmark, have very low maternal mortality ratios compared with the OECD average.

Whether one accepts all of Grantham’s political conclusions or not, this is where the episode becomes more than a market call. It becomes a critique of what modern wealth is for.

The most memorable moments

The first memorable moment is Grantham’s rejection of the S&P 500. Bartlett sounds genuinely surprised, which helps the exchange land. It is rare to hear a mainstream business podcast guest tell a broad audience not to own the default asset of modern passive investing.

The second is the SpaceX clash. Bartlett’s “I’m an investor in SpaceX” admission gives Grantham’s criticism a human target. It stops being abstract. Grantham is effectively telling the host that one of his exciting private investments may be part of the speculative excess he is warning about.

The third is the crypto exchange. It is brief, but the bluntness makes it unforgettable.

The fourth is the fertility discussion. The move from AI bubble to sperm counts sounds bizarre on paper, but the episode makes it feel like part of the same story: humans are bad at noticing slow-moving risks until they become emergencies.

The fifth is Grantham’s closing idea that he would like to write something with the societal impact of Silent Spring, focused on toxicity, family formation and the social contract. That moment explains why he is not merely a finance guest. He is a systems pessimist with an environmental mission.

About The Diary Of A CEO

The Diary Of A CEO is hosted by Steven Bartlett and has become one of the biggest interview podcasts in the business, self-improvement and ideas space. Apple Podcasts lists the show in the Business category and describes Bartlett as a British entrepreneur, investor and author who created the podcast to share “unfiltered” lessons from CEOs, experts, therapists and leaders.

The show’s official description frames it as a curiosity-driven interview format built around influential people, untold truths and lessons that can help listeners live better and more successfully.

This episode fits the show’s identity almost perfectly. It has a famous guest, bold claims, self-improvement relevance, money advice, existential risk, health warnings and a title engineered for urgency. It is not a quiet specialist interview for institutional investors. It is a mass-audience conversation about what to do when the future looks both exciting and unstable.

Bartlett’s strongest skill here is translation. When Grantham uses market language, Bartlett pulls it back to the listener: What is a bond? What does this mean for someone with a salary? What should a founder do? How should a young person think about skills?

That makes the episode accessible, even when the topics are huge.

About Jeremy Grantham

Jeremy Grantham is the co-founder of GMO, the Boston-based investment management firm. GMO’s official profile says he co-founded the firm in 1977, serves as long-term investment strategist, chairs the GMO board, and was previously a co-founder of Batterymarch Financial Management, where he recommended commercial indexing in 1971.

Grantham is known for his long-horizon, contrarian views on bubbles, valuation and mean reversion. His reputation rests partly on warnings around major speculative episodes, including Japanese equities, the dot-com era and the housing bubble. That reputation is central to why this episode works: listeners are not hearing a random pundit predict doom; they are hearing a market veteran whose entire public identity is built around spotting excess early.

He is also closely tied to environmental philanthropy. The Grantham Foundation says it was established in 1997 by Jeremy and Hannelore Grantham and is focused on protecting and improving the global environment.

That background helps explain why the episode moves so naturally from investing to climate, fertility and social systems. Grantham sees markets as part of a larger ecological and social picture. He is not only asking whether Nvidia, Tesla, Microsoft or SpaceX are overvalued. He is asking whether a society addicted to growth, optimism and short-term incentives can still protect its future.

The larger context behind the conversation

This episode arrives at a moment when AI is doing two contradictory things at once. It is producing real productivity gains, real products and real changes in how people work. It is also producing feverish capital spending, corporate rebranding, speculative valuations and a sense that every company must have an AI story.

That is exactly the kind of environment Grantham likes to analyze. His historical framework is that markets extrapolate. When things are good, investors assume they will stay good. When growth stocks dominate, investors treat that dominance as permanent. When a handful of companies become winners, investors assume those companies will own the future too.

The “Magnificent Seven” discussion captures this perfectly. Grantham argues that these companies once dominated separate lanes: search, smartphones, social networking, cloud, chips, electric vehicles, retail and software. But AI pushes them into the same ring. Instead of seven comfortable monopolies, he sees a brutal competition for the same prize.

That is one of the episode’s best insights. Even if AI becomes wildly important, it does not follow that every current winner earns monopoly profits from it. Competition can transfer value from shareholders to customers, suppliers, employees or infrastructure providers. The technology can win while many investors lose.

The fertility and toxicity discussion belongs to a different but related context: the growing public concern over endocrine-disrupting chemicals, microplastics and reproductive health. The evidence base is not as simple as a podcast soundbite can make it seem, but the concern is real enough to be part of mainstream scientific discussion. PubMed-indexed research has reported sperm count declines, microplastics in reproductive tissue, and associations between pesticide exposure and semen quality.

The inequality discussion also lands in a politically charged moment. Grantham’s comments on the US, Denmark, Norway, Sweden and broader social safety nets are not just lifestyle advice. They are part of his argument that societies with weaker social contracts become more fragile.

What the episode gets right

The episode’s biggest strength is that it does not treat investing as a spreadsheet exercise. It treats markets as human systems. Grantham is at his best when explaining how optimism, incentives, career risk and crowd behavior can overwhelm rational analysis.

The second strength is the historical framing. Railroads, the internet, Japan, the dot-com crash and the Nifty Fifty give listeners a way to understand AI mania without needing to predict exactly when anything breaks. Grantham’s point is not that history repeats mechanically. It is that humans repeat emotional patterns.

The third strength is Bartlett’s accessibility. He stops to ask basic questions that many listeners may be too embarrassed to ask. What is a bond? How do you buy one? What does “equity” mean? Why would an advisor not tell you to exit the market? Those questions make the episode much more useful for a general audience.

The fourth strength is the tension. Bartlett does not challenge every claim with equal force, but the SpaceX exchange proves he is willing to push back when the topic touches his own experience. That gives the interview more life than a simple doom monologue.

The fifth strength is scope. Some listeners may find the jump from AI stocks to sperm counts too wide, but it gives the episode a distinctive identity. This is not just another “market crash coming” video. It is a conversation about fragility.

What could have been better

The episode’s biggest weakness is that it sometimes lets dramatic claims outrun careful qualification.

The investment advice section, for example, is compelling but broad. “Don’t own US stocks” is a powerful line, but listeners need more framing. Does that mean zero US exposure? Does it apply to a 25-year-old retirement investor? Does it apply equally to someone in the UK, Sweden, Canada or the US? How should taxes, pensions, currency and risk tolerance change the answer? The show gestures at practical investing, but the headline claim is stronger than the nuance around it.

The crypto section could also have gone deeper. Grantham’s skepticism is clear, but Bartlett could have tested it against the best version of the opposing case. The same is true for SpaceX. Bartlett challenges Grantham emotionally and practically, but a more detailed breakdown of valuation, revenue assumptions and private-market liquidity would have strengthened the segment.

The fertility discussion needs caution. The research is serious, but the public conversation around sperm count decline is often filled with overconfident extrapolations. The episode would have been stronger if it had more clearly separated “observed decline,” “possible causes,” “animal or tissue findings,” “human association” and “future projection.”

Finally, the episode’s title is effective but sensational. That is part of modern YouTube, and The Diary Of A CEO is hardly alone in using high-stakes packaging. Still, a title like “I’m SELLING Everything” can make a nuanced conversation feel like a one-command emergency broadcast.

How listeners are reacting

A reliable sample of YouTube comments was not available during this review, so it would be unfair to invent specific audience reactions. What is clear is that the episode is moving quickly. Search snippets listed the YouTube episode at about 2.6 million views roughly one day after publication, suggesting unusually strong early attention.

The likely debate is easy to predict. Some listeners will see Grantham as one of the few market veterans willing to say what Wall Street will not. Others will see him as a long-running bear whose warnings can be directionally interesting but painfully early. Crypto supporters will reject his Bitcoin comments. Tesla and SpaceX believers will argue that betting against Elon Musk has historically been dangerous. AI optimists will say that massive investment is rational because the prize is enormous.

That mix is exactly why the episode is built to travel. It gives almost every major internet finance tribe something to argue about.

Is this episode worth listening to?

Yes — with the right expectations.

This is not a step-by-step financial plan. It is not a neutral academic panel. It is a strong, opinionated interview with a guest whose worldview is built around spotting long-term excess, environmental risk and social fragility.

Listen if you want a provocative case against US equity complacency, a historical argument about AI as a bubble, and a broader discussion about what happens when societies ignore slow-moving threats. Skip it if you want balanced portfolio construction, detailed crypto debate or a purely technical AI conversation.

The episode is especially useful for founders and investors because Grantham’s warning about capital availability is practical: when money is easy, raise it; when conditions tighten, fragile companies discover how little patience the market has.

Best quotes and ideas from the episode

The episode’s most important ideas are better paraphrased than quoted at length:

One: AI can be transformative and still produce terrible investment outcomes for late buyers.

Two: the more obvious a revolutionary idea becomes, the more likely too much capital piles into it.

Three: large investment firms rarely have an incentive to warn clients loudly at the top of a bubble.

Four: US market dominance may be a cycle, not a permanent law of nature.

Five: SpaceX may be a brilliant company and still carry fantasy-level expectations.

Six: crypto, in Grantham’s view, remains speculation rather than a reliable store of value or everyday medium of exchange.

Seven: fertility, toxicity and inequality are not side issues; they are signs of whether a society is protecting its future.

Eight: no help is coming from institutions if the incentive structure rewards optimism.

Final verdict

The Jeremy Grantham Diary Of A CEO episode is one of the most provocative finance interviews of the week because it understands that market bubbles are never only about markets. They are about stories people want to believe.

Grantham’s story is bleak: AI may be real but overpriced, Wall Street may be conflicted, US stocks may be dangerously expensive, Bitcoin may be destined for zero, SpaceX may be floating on fantasy, fertility may be under chemical assault, and the US may be weaker than its headline wealth suggests.

That is a lot for one podcast episode. At times, it is too much. But the ambition is also what makes the conversation memorable. Bartlett keeps the discussion moving, translates jargon for a mainstream audience, and lets Grantham make the kind of big, uncomfortable claims that produce real debate.

The episode is not valuable because every prediction will necessarily be right. It is valuable because it forces listeners to ask whether they have mistaken a powerful trend for a safe investment, a rising market for a healthy economy, and technological magic for guaranteed returns.

FAQ

What is the Jeremy Grantham Diary Of A CEO episode about?

It is about Jeremy Grantham’s warning that AI may be the center of a major investment bubble. The episode also covers US stocks, bonds, Bitcoin, SpaceX, housing, fertility decline, toxic chemicals, inequality and social trust.

Who is the guest on this episode of The Diary Of A CEO?

The guest is Jeremy Grantham, co-founder of GMO and long-term investment strategist. He is known for his contrarian market views, warnings about bubbles and environmental philanthropy.

Who hosts the episode?

The episode is hosted by Steven Bartlett, the entrepreneur, investor, author and host of The Diary Of A CEO. Apple Podcasts describes Bartlett as the founder of Flight Story and Flight Fund.

How long is the episode?

The episode runs about 1 hour and 45 minutes. Apple Podcasts lists it as 1hr 45min.

What did Jeremy Grantham say about AI?

Grantham argues that AI is a major technological breakthrough but also potentially the biggest investment bubble in American history. His main point is that important technologies can still become overfunded and overpriced.

What did Jeremy Grantham say about US stocks?

He argues that US stocks are badly overpriced and says ordinary investors should consider broad non-US equity exposure instead. This is one of the episode’s most controversial claims.

What did Jeremy Grantham say about Bitcoin?

Grantham says he does not own crypto and believes Bitcoin will eventually go to zero in the distant future. His criticism is that crypto is too volatile and too speculative to function as a reliable store of value.

What did Jeremy Grantham say about SpaceX?

He criticizes SpaceX’s valuation story, especially claims tied to future AI, space infrastructure, asteroid mining and Mars ambitions. Bartlett pushes back because he is personally invested in SpaceX.

Is the episode financial advice?

No. It should be treated as a podcast interview and opinionated market commentary, not personalized financial advice. Listeners should consider their own situation and consult qualified professionals before making investment decisions.

Why is this episode trending?

It combines a famous contrarian investor, a huge podcast platform, a dramatic AI bubble warning, anti-crypto comments, a SpaceX debate and practical-sounding investment advice. The episode also gained rapid early viewership on YouTube.

Is the episode worth watching?

Yes, especially for listeners interested in markets, AI, investing psychology and long-term risk. It is less suitable for people looking for a balanced panel debate or a detailed personal finance plan.

Where can you watch or listen to the episode?

The episode is available on YouTube via The Diary Of A CEO channel and on podcast platforms such as Apple Podcasts and Spotify. Apple Podcasts lists it under The Diary Of A CEO with Steven Bartlett.