Accepting loss is hard because we've used a few dollars to gamble and it didn't turn out as we hoped because we lost. And if you have lost many times, we should really have to rest for at least a few days. I often take long breaks after losing for a few days, maybe around 1-2 weeks, before starting to play gambling again. And so far, it's been working for me. Maybe he should find another way to refresh his mind after a defeat so he won't think about the previous loss.
In fact, we have all reminded each other that it is better to gamble responsibly and use a small amount that we can afford to lose, so that when we lose we can always accept the loss.
But if you ignore gambling responsibly, I'm sure you will always be disappointed and cannot accept losses from that defeat.
But I understand these situations and conditions because sometimes a gambler will feel greedy with small results so he is forced to gamble with even more money to chase big wins.