Yeah, it's rare to practice it but there are few or some gamblers who already gained their experienced they managed to keep that control and played with a discipline ways to avoid losing a lot, your set example is valid as there are factors that really breaking in your way but if the dedication and that self-will really focus into something that will benefits you, once you acquire the high level of it then it surely do the best for you.
If people were disciplined in Spending money, Believe me, there Would be no Addiction Problems, much less, but everything fails in the Basics , and it is incredible, many fight for their Money in anything, in accounts, in something like that, but When they should take care of it and Protect it, they do not succeed, what will happen with that? because things will always be very focused on Doing them well, when it comes to casinos and everything required, that force of discipline is not there.
It may sound very trite about discipline, but it is the truth, everything Depends on that if we look at it from a focus closer to Reality.