Trading seems to have people from a very wide variety of backgrounds and capabilities. I think it's the result of random events being the most significant filtering mechanism. Anyone can get burned on a trade at any time, so staying in the game doesn't really depend on anyone's qualifications or abilities.
And, if anything, people from less secure socioeconomic backgrounds may feel they stand to lose less by pursuing a riskier career path (and I mean "risk" in the real sense of a broader range of outcomes) than, say, PE or Corporate Law, so they are a larger share of S&T
Feel like for trading you either have it or don't, and no pedigree will save you on a bad trade.