Some gamblers do not know when they have lost control and just keep gambling and also trying to recover their losses at all means which in most cases do not end well.
I agree with you that every gambler should try to have self discipline and  also try to have a self check and also try to have a pause when it’s necessary so they can always get to check their gambling habit.

I also think that, have a gambling budget if possible will help to keep a gambler in check so that they do not gamble more than expected and the ability to abide by this budget is discipline as many people might have a budget but find it difficult to abide that it.