While rational expectation is returning to part of the investment community, most investors are still trapped by institutional weakness, which makes them behave irrationally. The Greenspan era has nurtured a vast financial sector. All the people in this business need something to do. Since they invest other people's money, they are biased toward bullish sentiment. Otherwise, if they say it's all bad, their investors will take back the money, and they will lose their jobs. Governments know that, and create noise to give them excuses to be bullish.
This institutional weakness has been a catastrophe for people who trust investment professionals....
Indeed, most people who invest in the stock market get poorer.