While there are many definitions about what it means to be a professional, one of them is simply about your ability to make money in any activity, so professional gambler is indeed the correct term for the people that can make money with gambling in a consistent basis, now the issue is that for every single professional gambler out there, there are hundreds of people that tried to achieve the same results and they failed to do it, as hardly anyone hears about their failures.
Alright buddy, I Don't want to be disagree without your opinion because your opinion is also right on the other point of view.
But what I mean professional means is connected to professions and professional means an person who are is well skilled on that sectors. And in this point of view we can't assume the gambling as a profession because gambling is all about luck and it is for only entertainment purpose.
And that is why I mentioned that here the word should be used responsible gambler.
Previously I was sure that you conveyed the opinion based on common sense and rational thinking, I agree with what you said and I think the idea of becoming a professional in gambling is something that sounds unreasonable, the reason is clear as you said that gambling is an activity that is quite dependent on luck, or although there are indeed several types of betting activities that can be done by applying skills and analysis but still luck is always the most important factor to confirm victory.
This means that there is something that a gambler can never learn, namely luck, because no matter what we will never know how to control luck so that it always sides with us, meaning that of course defeat will always be a certainty, and I think it makes no sense to set a goal of becoming a professional in a profession that in fact cannot be learned.