Most gamblers are seen chasing profits in gambling. You cannot handle it with emotions. Here people associate their emotions with their psychological standards. By learning to control emotions, you can prevent yourself from losing more in gambling.
The attitude of chasing losses is the reason why some new gamblers would think that gambling is a scam because they have lose a lot of money that they never have intentions of losing. Like you said, self control can help them become better gamblers but they still have the decision to make concerning how much they want to spend on gambling or not.
I have seen that there are many gamblers who are new and have no experience in gambling, but they are quite interested in playing it, and those new gamblers face more losses. When they lose their money, they consider gambling as a cheating trap, but those stupid people do not know that they are facing losses because of their lack of knowledge and experience. Yes, there are many gamblers who cannot decide how much money they will spend on gambling, they lose money due to such self-control, so it is necessary to know well at the beginning of gambling.