The most profound way I changed my mind:

When I was a child, I thought betting was like playing with matches.  Only fools did either.  The habit stuck through my twenties until I met Robin Hanson

Hanging out with Robin didn’t just make me lose my prejudice against betting.  He led me to my current view: intellectuals who refuse to bet on their beliefs are tricksters, frauds, phonies, eels, and blowhards. 

In slogan form: I used to think people who bet were fools.  Now I think people who don’t bet are knaves.