By 30 years old, Sam Polk had made more than $5 million in bonuses alone during eight years working on Wall Street. As a trader, he was living it up in Manhattan by the age of 25, able to count on a cash flow and perks that would be the envy of many.  "It was an easy thing to go to a World Series game, which for a lot of people was like a dream," he tells us in the accompanying video as an example. Couple the perks with the seven-figure bonuses he was on track to earn and Polk had "a tremendous feeling of importance and power especially as a 25-year-old kid."

Related: How one Wall Street trader blew through $10 million

But at 30, he abruptly decided to leave the Street. Despite the money Polk had been making, over the years he found himself nagged by envy. In a New York Times op-ed, he describes working at bulge-bracket firms like Bank of America (BAC) and Citigroup (C) early in his career, on trading desks where everyone sits together and perspective goes out the door -- when you sit next to someone making $10 million, your $1 to $2 million compensation doesn't look so great.

He went on to work at a hedge fund, and his obsession with money only got worse.

He writes in the NY Times: Now, working elbow to elbow with billionaires, I was a giant fireball of greed. I’d think about how my colleagues could buy Micronesia if they wanted to, or become mayor of New York City. They didn’t just have money; they had power — power beyond getting a table at Le Bernardin. Senators came to their offices. They were royalty.

Polk describes getting angry over a $3.6 million bonus because it wasn’t big enough.

He came to believe that he personally had developed a wealth addiction.

"One of the things I came to realize was I had been using money as this thing that would quell all my fears," he explains. "So I had this belief that maybe some day I would get enough money that I would no longer be scared ... I would feel successful. And one of the things I learned on Wall Street was no matter how much money I made, the money was never going to do it.

In the end, he writes that it was observing his "absurdly" wealthy bosses that helped him realize the limits of unlimited money:

I was in a meeting with one of them, and a few other traders, and they were talking about the new hedge-fund regulations. Most everyone on Wall Street thought they were a bad idea. “But isn’t it better for the system as a whole?” I asked. The room went quiet, and my boss shot me a withering look. I remember his saying, “I don’t have the brain capacity to think about the system as a whole. All I’m concerned with is how this affects our company.” I felt as if I’d been punched in the gut. He was afraid of losing money, despite all that he had.