Stock price is 100% based on demand and nothing else (well aside from new issuances or splits). Demand is ideally a function of fundamentals. The stock price

Stock price is 100% based on demand and nothing else (well aside from new issuances or splits). Demand is ideally a function of fundamentals. The stock price being overvalued is irrelevant if “everyone” is buying it. This is a hyperbolic example but it plays out in the valuation of the sp500 when legions of folks just dump into an index fund.