~snip~
Very different and strange take on this topic but it feels like undeniable truth that someone should be making money to be counted true professional. Otherwise its just hobby lol. I saw no video gamers claiming they are professional unless they join as team, find a sponsor, get wage, win contest etc so on. At the point where a gambler can generate money through he can be called pro. I think we may count sponsorships too - gambler doesn't need to be always making money only through gambling he is mastering.
Well, that's true, you can be a professional YouTuber showing your gambling on your channel for example, because you are getting paid for the ads that you run on the channel.
As long as you actually get money from something you are doing, instead of paying for doing it, then you are a pro, a professional. That's how you "turn pro", when you start making money with anything.