Professional gambler huh? I think that's a term I haven't really gotten used to because it's just not something am familiar with or it's just that I don't really believe that some people are actually professionals when it comes to gambling and besides on what context are they even professional? Is it that they don't lose or they are very good with there are gambling habits . If am not mistaken, gambling is something that anyone can lose control and do something stupid even the so called professionals, it's takes just a bad decision.
On this case the word professional is being used with the meaning of someone that can profit from an activity, so as an example, if someone was a carpenter and they were terrible at it but they were still earning money with it, it is fair to call them a professional carpenter, even if they did not had the skills and abilities that many other carpenters take for granted.
The truth is that professional gamblers are very rare, probably less than 1% of all the gamblers, and yet the majority of them aspire to one day reach that goal, despite knowing it is incredibly hard to do so.