This is possible because once he has recovered from his addiction, he can gamble calmly, not chase after winnings, and gamble in moderation. He was completely different from when he often gambled before in that he didn't have good self-control. His current self-control is so different from before that he will not gamble beyond his limits because he knows what will happen to him if he crosses his limits. Indeed, he cannot win more often because it will depend on his luck, but at least he can limit himself to gambling and not make gambling something that can give him money. He can treat gambling as a form of entertainment as it should be.
Is there really such a thing as recovering from a gambling addiction and still playing? I don't think so. What I think is that he gained experience by playing multiple times and he came up with some of the tricks and ideas on how he will be able to win. But the addiction will be still. If we're talking about recovering from gambling, there's no reason for a gambling addict to continue playing.
Yeah, one might actually be able to recover from their addiction and reduce the time and money that they used to spend on gambling and become a responsible gambler after that. However, I don't think that once a person has left gambling and got rid of their addiction, should gamble once again because when you have already been addicted to something, you can easily get addicted to that thing again if you start doing it more often.
So, someone who has already managed to get out of their gambling addiction and are easily able to stay away from gambling, they should do that instead of getting involved again because they might be able to be responsible at the beginning, but they will eventually start getting addicted to it again.