If you're a gambler, then control and manage how you're gambling before it get worse to the extreme stage, also, if you're privileged to see someone gambling in the wrong direction, take it a responsibility to call them into order, some things were better done or dealt with in the early stage before they got worsened, having desires for gambling is not getting yourself harmed by gambling because if ignorance or lack of self control while gambling, the gambling platforms will not control you, it's your own responsibility to do so for yourself.
It is very rare that people listen to others when it comes to this as they will feel judged, and they will think that you are overstepping their boundaries by doing something like this, so even if you were correct on your observations about their gambling habits, you can bet they will continue to gamble as usual, and even if at some point they realize they had a problem you can be sure they will not remember that you tried to help them before things got out of control.
It really depends upon oneself if he or she wants to exclude himself from gambling or quit gambling in simple words. You can lock your money in some other things, do not have access to your money and other such tactics may help you to refrain from gambling for a short time but if you want to keep yourself limited to gambling, then you may need to be strong enough and your mind needs to be focused so that you do not over gamble.
The strength of self-willingness is something which can't be compared to you put restrictions on the access of resources to do gambling.
If we really want to be responsible gambler, our focus should be top notch and our will power will determine if we are able to control our emotions.