Well look at it like this: Why did so many vote for Bush when he has not been right on a single thing besides give cronies a tax cut? In other words, how could so many think they were so right when they were so wrong?...
95% of equity "TRADERS" never last to see the long term. Tons of long term equity "INVESTORS" get that way by hanging on to the losers. The winning profits were taken long ago..... I wonder how long the average holding period was for a super stock trader like michael steinhardt was... Even michael made a boatload of cash when he bet right on the bonds as Volchker came to the end of raising interest rates to kill the inflation of the late 70's early 80's time frame.
There's one feature / flaw in the intelligent / or not design of the humans: same data input into two humans may give opposite results. Even more: same data input into the same human at two different moments may give as well opposite results. This is why when humans decide through majority it is called democracy (and the decision may be right or may be wrong), and when computers decide through majority it is called redundancy (and the decision is always right, except when the design is poor and the decision is always wrong).