Making the Schiller group psychology theory bogus

Diversify? Almost half of Warren Buffett’s Berkshire Hathaway portfolio is now composed of a single stock

Different people at different times.  If they are different people then mass psychology does not apply.

Schiller need variance, mean and skew to account for his theory. The stock market is not a thing, it is an accounting standard for equities and it has no time variable. It can only be treated as an independent probability distribution.