Sam Polk started out on Wall Street fresh out of college. It was 2003, and the young trader was surprised to learn that one of his Bank of America colleagues had two Ferraris.

By the end of his first year, he had a $40,000 bonus. It was intoxicating, and he soon threw himself into the world of bond and credit default swaps. But even as he earned $1.5 million at the end of his second year at a hedge fund, Polk still felt jealous and worried that he wasn’t making enough.

"I was using money to fill this hole inside me," he said. "It’s very hard to sort of maintain your own values amidst a system that values something different."

And when the 2008 stock market crash happened – which Polk likened to "being on roller skates on a ship in the middle of a storm" – he didn't lose money. He actually profited by shorting derivatives of risky companies.