The assumption of perfectly rational, maximizing behavior won out until recently in the art of modeling, not because it often reflects reality, but b… - Didier Sornette

A bubble that goes up is just one that could have crashed but did not.

It is difficult to assess how much this gambling spirit is active in the minds of individual investors. If it is, even to a small degree, it is relevant to our discussion since it makes investors prone to imitation and herding because they invest on little information. It may also explain the anomalously large volatility of prices and their potential instabilities.

Finally, empirical data suggests that assets are sold much more slowly during retirement years than when they are accumulated during working years.