You are not a professional unless you gamble professionally for a living like poker players. That is the only thing. You can act professionally, but that is something else and you would just be considered a disciplined amateur. To act professionally you need to check all the boxes like discipline, strategy, bankroll management and such things. If you miss on any of them then you aren't really good at this.
Seriously, I don’t think they will be a professional in gambling. We all know that there are a lot of people who have been gambling for a while andstill lose whenever they place a bet. Because not every one of their predictions comes true, that’s why I said I don’t think they will be a professional in gambling. Since gambling is all about luck, there are some people that are very smart when it comes to gambling, and they also lose sometimes.
The reason why so many people classify themselves as professionals in gambling is because they think that they have been experts in gambling and winning every single day in gambling. That doesn’t make the person a professional.