Today's massive AI company valuations are based on market sentiment ("vibes") and debt-fueled speculation, not fundamentals, just like the 1999 internet bubble. The market will likely crash when confidence breaks, long before AI's full potential is realized, wiping out many companies but creating immense wealth for those holding the survivors.

Unlike past bubbles (e.g., railroads), today's investors explicitly justify AI overspending by citing the eventual positive outcomes of prior bubbles. This creates a self-reinforcing, reflexive loop that encourages even greater excess than was seen in previous historical cycles.

The current AI investment frenzy follows the classic bubble pattern of leverage and greed seen in the dot-com era and the 2008 subprime mortgage crisis. This historical parallel suggests that AI, despite its potential, is susceptible to a similar dramatic collapse, possibly originating in private credit.

The current AI boom mirrors the dot-com era. The underlying technology is revolutionary and will transform the economy, but valuations may have already priced in decades of future growth. This means investors buying now risk poor returns even if the companies ultimately succeed, as both technology enthusiasts and valuation skeptics can be correct simultaneously.

Tech giants are spending hundreds of billions on AI infrastructure with slow initial results, reminiscent of the Web 1.0 era's overbuild of fiber optic networks. This parallel suggests a potential AI bubble where the infrastructure is built, but the equity holders who funded it get crushed in a market correction.

Investor Howard Marks notes that every major technological revolution, from railroads to the internet, has produced a money-losing bubble. The current AI excitement, characterized by the belief that "no price is too high" and that rules have changed, mirrors the psychology of past bubbles, suggesting extreme risk for investors.

Grant believes the excitement and capital influx into AI dwarfs the 1990s internet boom. He argues it's fueled by a speculative spirit and potential miscalculations of supply and demand, much like past technological manias, rather than by sound analysis.

The market narrative around AI—where participation feels mandatory and valuations seem justified by future growth—is reminiscent of the dot-com era's Cisco mania. However, the capitalizations and total addressable market claims today are orders of magnitude larger.

History shows that major technological breakthroughs—from railroads to the internet—are the very things that fuel speculative bubbles. Investors mistake a transformative technology for a guaranteed good investment, ignoring valuation. This is because bubbles form around things people genuinely believe are world-changing, not obvious fads.