It is true that with good self-control possessed by the gambler, he will gamble by setting the right limits every time he will bet money, good self-control is very useful for gamblers besides they can set limits on money to bet there are also other benefits as you have mentioned, namely controlling the emotional feelings that exist within a gambler.
Yes, it is true that someone who has good self-control will be far from bad attitudes such as greed can be controlled by the existence of good control and what can a gambler do, he will feel safer if self-control is done properly.
That is how limitation will helps gamblers to prevent his losses in gambling so they can enjoy for playing gambling while they don't have to lose much money. If many gamblers realizes about that and will not use too big money to playing gambling, they can use gambling for having fun and will not trying to chase the win. They know that can makes them becomes emotional and when that is happen, they will lose control over themselves.
The emotional feeling can besides them while playing gambling and can change anytime based on what they gets from gambling. But if they have a strong self control, they will not have to worry if that will hurt them because they can playing gambling moderately. They can manage themselves not to becomes emotional and the important thing are they can stops from playing gambling anytime they want.