Since your friend is adamant to heed your advice and stop chasing his loses, what you can do is stop loaning him money, except you're very sure that it won't be used for gambling. He is still addicted to chasing his loses because he still has ways of raising his gambling funds, if he runs out of ideas and avenues to raise money for gambling, then it'll be a full stop to gambling. Your friend really needs help to overcome his addiction and it'll start with him admitting that he has a gambling problem. I guess that sooner or later when there's no more money to gamble, he'll admit that he needs help. Keep encouraging him to stop until he makes that decision.