Is been responsible with gambling all it takes to be a professional gambler or someone needs to win in the process many times already to be considered a professional gambler?
What if he is just extremely lucky that is why he keeps winning? Is that called a professional gambler already? Anyone can be lucky and anyone can be responsible but I would not just call anyone a responsible gambler.
What is a been qualified as a professional gambler in your own world? The winning part or the responsible part of trying to avoid addiction is all.
Probably someone who uses gambling as a source of income. If he has learned how to play a game that uses strategy then that may be considered as professional.