~snip~
This would help a lot of people around the globe to maintain control over their asset and help them set the right thing to do in case when the limit have been reached. But, I think this would be hard to be implemented because, I think, it would mean less opportunity for the gambling organizers to earn more profit, it is either they would implement it themselves' which is less possible, or a regulating body would take charge.
Even if the gambling site makes an easy way to prevent members from gambling, if the gamblers don't have self-control, that gambler will always gamble and use more money. If there is a prohibition or limiting on using the money for gamblers or the account will freeze by itself if the gamblers break the limit, that doesn't mean the gamblers will stop playing gambling. They will open a new account in the other days to play gambling, and that will happen like that over and over. So every gambler really needs to have self-control over themselves.
This may not be able to totally hinder an addicted gambler from playing. But to a moderate gambler who is attracted to gambling but still has some control left in him, this might really help. This is an effective mechanism to manage each gambler's gambling hobby. But if we talk of addicted gamblers, that would be a totally different scenario. Gambling is almost unstoppable for this kind of people. Even without a single penny, they will always find a way to gamble, either by selling some properties, or by stealing, or pawning, getting a loan, and so on. So this feature is definitely not for them. What is for them is professional intervention.