Some people work to pay the bills. Some people work to achieve power. Some people, like us, are so passionate about creating things, the prospect of being able to create with no rules, no oversight, and no strings attached is just about the most appealing job in the world.
Bret accurately summarizes what most closet entrepreneurs feel when they realize the corporate machine has nothing more to provide than a paycheck. Entrepreneurs by nature will want to break out of the constraints set by corporate structures and will seek or long for the exciting/nervous/scary/puke-inducing highs and lows of choosing their own path.