Following your sentiment, there's no assurance that you can win in every play that you participate, chances of losing is always on your back and even how many times you manage to win there's always a bad day for you, though if you can control yourself and you can manage your emotion which is for sure that only a small percentage of gamblers can, there's always a possibility that you will lose your control and also suffer from big defeats.
As a career maybe it's only few person can deal with it, most might have other things or other alternative aside from gambling that can give them enough financial needs in case they lose in gambling.
The fact that people do not realize that the losing streak possibility becoming major when they gamble more is the problem. If you want to make it a "profession" then you need to gamble a lot, this isn't really about getting lucky once, it is about the fact that we are talking about something that would be a big situation, and this is why I think it has to be something that would not be all that easy.
I hope that the best thing to do would be nothing too worried, and that has to be the situation. I think we are going to end up with a trouble if we are not careful. So all in all we need to end up with a situation that will not be all that easy, so all in all do not gamble professional because most likely that you are going to lose.