Thus, there is really no professional here. You can't help yourself from losing in gambling if your luck isn't favorable of you but to stop. Meanwhile in day trading, you might lose continuously but you can be professional there with decent experiences and knowledges of course.
Everyone has different belief, some would say no professional gamble but some would believe there is because they themselves are professional gambler.
Because what do we mean exactly by "professional"? Is it because we are on it full time? Or is it probably because we are earning only from it? Or because we have undergone some kind of training or course for it? What we call "professional" is rather hazy and could mean different things.
There are indeed professional gamblers if we consider the factor of income source or full time dedication and focus just like there are also professionals in trading.