Simply put, everyone who experiences defeat will easily learn to control themselves, because they have previous experience. Personally, I believe that everyone has different weaknesses and strengths, therefore everyone will have their own limits that are formed based on that experience. Self control can help increase the chances of winning, it will also help someone focus when analyzing the game. Many people experience continuous losses due to failing to control themselves, although sometimes experienced people also have the potential to act beyond the limit. Luck is preparation to meet opportunity, one thing that must be learned is self control.
Constant losses can also be the result of poor analysis. For example if a person is able to control themselves well but makes bad match analyses and poor betting choices then self control will not help them in any way. You need to be a good analyst and you need to have a good win rate so that losses are a rare thing. That is why success in gambling is a complex approach. We analyze well we control ourselves we manage our budget we manage our bets and that is probably what emotional control really is.