Since it is the actions of investors whose buy and sell decisions move prices up and down, any deviation from a random walk has ultimately to be trac… - Didier Sornette

The acceleration of the number of traders buying into the market in the inflating bubble captures the oft-quoted observation that bubbles are times when the "greater fool theory" applies.

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.

These rumors do not circulate in all directions, but essentially from the top to the bottom of society. The rather sophisticated presentations, the apparently serious references that seem to justify their origins, and their distinguished proponents provide food for amplifications serving diverse interests and psychological biases in all layers of society.