I'm *uming that you're not talking about people who are rich already, they can clearly do this. Beyond the rich, I'm sure there are some people who make a living from their investments. I bet many more have tried and failed though. I would compare it to trying to succeed at something very competitive, like playing poker professionally. You have to be extremely good at what you are doing, and have a lot of discipline. These careers are possible for a few exceptional people, but they're too difficult for most to succeed at.