I don't think or believe there is anything called a professional gambler, in fact let me break it down a bit. When talk about professional we are referring to someone who can control themselves while gambling and also knowing when to stop, when to start and how much they should used to gamble or not to gambling. When all these are being put in places we can say that such person is a responsible gambler, because they weren't allowing gambling to over-will them neither are they gambling for money making even though our attention is being focused on that but at least they are also bearing the risk by using what they can afford to lose while gambling.
All the qualities you mentioned are already part of what a professional gambler has. They call themselves that because they’re in it to make money, not just for entertainment. But let’s not assume that being a “professional” means they’re raking in tons of cash. Some are profitable, some aren’t, the only difference is they take gambling seriously. Still, no matter how skilled or experienced, the outcome is never guaranteed.
Of course we can't guaranteed the outcome of gambling that is why it is a game of probability and not certainties, when someone bet on a game the possibility of that person making winning is 50/50 chances and is either the person lose or win. So, while gambling it is always advisable to gamble with what we can afford to lose than what we can't seems to control our emotion when we loses, gambling is fun and yet there is also need to look at the out come if is that suitable and profitable to us, it is also good to look at our results if we are making progress or not, and of course we should draw close attention to how much we also uses to gamble.