This is why it is important to have self-control when gambling and never consider gambling as a means of making money, gambling should be seen as just a part of entertainment.
That is the main thing, we as people must see that the main thing in all this is fun and that it cannot be denied that when we enter a casino what we want and look for is to make money, but above all self-control is based on emotions, that is why even with all this, I continue saying that the best method for us to control everything is to control the money that we are willing to lose , that for me is the trick of everything, what they say they can control emotions is good, but nothing is as infallible as controlling money.
On that, you are very correct @LUCKMCFLY.
I do believe that emotions is something that will always arise no matter how one tries to control it but one good way to control it is to have a set up rule that the gambler must follow, like the aspect of controlling how much that the player is willing to lose, just as you said. I think if a player do write down those rule and always read it out loud to themselves before going to the casino, it could help.