My pool cleaner, like most of us, has a finite lifespan. While it's certainly theoretically possible that he could have been a hedge fund trader for Goldman-Sachs, I think we can both agree that to accomplish that would've required a fair amount of luck somewhere along the way. He might, by grit and discipline and sacrifice, have managed to become a lawyer, and make more than he is making as a pool cleaner. But to become independently wealthy by age 30, he also would've had to be very, very lucky.
Looked at in this light, only a small percentage of the population has any chance at tremendous success.
Not only that, but only a small percentage of the population has ready access to the positions that offer the financial leverage necessary for that kind of success.