How millionaire bankers actually work, according to a former trader

Gary Stevenson, the author of "The Trading Game," spent his early 20s trading trillions of dollars for Citibank in London and Tokyo.

He says he won the job playing a card game. While some of his colleagues lived a life fueled by partying and cocaine, Gary earned millions betting against the global economy. He talks to Business Insider about office culture in Canary Wharf, London; the bosses; and the bonuses. He covers the mindset of profitable bankers, their daily routine, and what leaving the job was like.