Even if you're very good, it's a gamble; almost all celebrity stories contain the element that they simply met the right person or were in the right place at the right time. And fame doesn't correlate with how good you really are; there are various famous musicians who aren't technically good at all, but got their breakthrough for some other reason. So it is almost impossible to plan a successful career a priori or to estimate its chances of success. Just like in a game of chance.