We as humans have to seek for something we are good at, that's adventure on it's own but threading carelessly can impact our true self and journey in life, trying to become a professional gambler is even more dangerous.
That thing that they are good at is what they consider a profession, and if we are to take it in that regard, most people already consider themselves to be very good at gambling, and as such, they can proudly say that they are professional gamblers even though they can't boast of 8 wins out of 10 games.
gambling is just something that I don't see safe for anyone to consider it as a precession because of its easy means of someone getting addicted to the game before even realizing it due to how constant they will need to be playing.