Any skill based game should have few professional players. However, I feel that a professional gambler is that person that can control his gambling activities by gambling responsible and limit his losses. On the other hand, if you feel that a professional is someone that wins more than losing in the long run, I don't think that we have someone like that. This is because, he will definitely be an addict which kills all the skills, fun and profits.
An addict may not possibly be losing the skills if they are also professionals in that field and happen to have more wins than losses. If they’ve lost those skills, then they won’t be called professionals because it’s the skill that makes them to be called one and not just by their addiction to it. However, some may still call themselves professionals because they’ve achieved more wins than losses in their games with no skills but just luck upon luck. So being a professional or addicted gambler, a skilled or luck based gambler all still falls back to how consistent you win and limit your number of losses in the overall game.