Traders who can truly make big money over the long term often have four abilities at the same time: mathematics, finance, psychology, and philosophy. Mathematics tells them where probability lies; finance tells them what the rules are; psychology tells them how to control themselves; philosophy tells them how to face uncertainty.

Therefore, what trading can really teach people may not be how to make money, but how to deal with a world full of uncertainty: admit that they can be wrong, accept that the world is uncontrollable, place bets within probability, and stay calm in the outcome.