I guess with this explaination, I can agree that such person can be called a professional gambler because he or she knows exactly when to quit when gambling and he or understand a winning in gambling cant be forced as every winning in gambling is purely based on the factor of luck. Some person I have come across in my area always claim that they are professional when it comes to gambling which they always mislead the definition of the word in gambling and deem it to be someone who always have consistent winning in gambling and claimed that it is the source of their living which I know is a pure lie, no one can make a living through gambling.
I have rarely Encountered people who know when they get out of the game and get Under profit, that is something I admire Greatly and I keep thinking how they do? Sometimes I think that the people who do that are that they have a gift and do it, I do not see another because Knowing well when going out is ex -teachers, and as you say, knowing at what time they should leave and at what time they Should bet is Some teachers, when Everything is in the hands of luck and the Coldness of Playing, I think that the best Results Occur is for that Reason, when I play Regularly I do it Betting little and very controlled so as not to lose everything The money at once.
Yes, people who can manage to quit even they've got some losses from their bankroll they can call for the day and quit their way to take time to breathe some air and relax their minds. It helps a lot to maintain yourself and control emotions as you take some time to re-assess your gambling participation and have yourself a rest to clean up all the messed that happened.
It's a great way to assure yourself that you are still in control and you are still on the track with the limitations that you setup.