Imagine shorting Nvidia in July 2023 last year at $500 because it seemed overvalued or overextended. now $700 like nothing. It goes to show how markets are more rational than assumed , in terms of correctly pricing in future earnings. It's not irrational exuberance, but rational. The huge rally this year was in anticipation of the blow-out earnings on Ai demand, which materialized . The 1997-2000 period in which stock prices wildly departed from fundamentals was more of an anomaly than the norm, yet people assume that it's the norm. The late 90s and tech boom and early 2000s crash was an outlier that made people overly pessimistic in subsequent decades.