I think that controlling emotions is very difficult even in normal situations when you are not winning,when you win it becomes even more difficult as the momental joy of winning makes you asking for more and this is the hardest thing to fight because our human nature is deeply based on greed,we want always more and more and that is what lead to gambling management as an almost impossible task for at least 90% of all the gamblers.
It means they didn't get paid enough from their jobs, so they choose to gamble in order to earn more. So the problem is they need to find other jobs that pays well or part time jobs, until they feel enough. When they didn't desperately to earn money, they will able to control their emotions.
The main problem of gambling addiction is money, we make money from working, not gamble.