I still can't decide which mechanism is at work:

Person is a nutter -> nutters more likely to be at the extremes of achievement (success and failure) -> you see the successes -> there's a bunch of insane people who became billionaires

versus:

Some people win at the success game -> they start to think they are special -> environment encourages them towards extremes of thought -> bunch of crazy billionaires

One way the negative traits are merely uncovered by getting rich. Other way the negative traits are actually developed along with getting rich.