Greed shifts to fear and panic. It has been happening for centuries and is not about to change. We can readily describe this process, but, to date, economists have been unable to anticipate sharp reversals in confidence. Collapsing confidence is generally described as a bursting bubble, an event incontrovertibly evident only in retrospect. I think this is sarcasm.
Bubbles are easy to see.
We are in one right now. The Japanese were in one in 1989. The consensus denies we are in a bubble, but on Wall Street, the consensus is usually wrong. Don't expect Wall Street to warn you, it is not in their best interest. To anticipate a bubble about to burst requires the forecast of a plunge in the prices of assets previously set by the judgments of millions of investors, many of whom are highly knowledgeable about the prospects for the specific investments that make up our broad price indexes of stocks and other assets.