I have to keep reminding myself that if nobody could outguess the market, then there'd be no money in trying to outguess the market, so only fools would enter it, and it would be easy to outguess.

There is the old joke about a student and a professor of economics walking on campus. The student notices a $20 bill lying on the sidewalk and starts to pick it up when the professor stops him. "Don't bother," the professor says, "it's fake. If it were real someone already would have picked it up".