The fear of losing money will cause regret when you win a bet. In my opinion, it is just an illusion that crosses someone's mind because they are unable to bear the loss when they lose. In fact, if he was able to think objectively, winning and losing are part of gambling, maybe this small win would not have happened.
It's obvious that everyone gambling knows very well that gambling is all about risk, and on the process of gambling you can lose what you stake, for me I don't think that it's nice to regret when you lose in the gambling, because we know very well that neither we win or we lose in the gambling, this two things is what that's involved in the gambling, so gambling is all about understanding and opportunity, you have fear in mind and stake in gambling and you may have the opportunity to win, and in other hands you can also fear can also contribute for a gambler to lose in the gambling, so this two things is something we are suppose to know of gambling, so when participating in the gambling you have to understand that gambling is all about taking care and also being calculative to know what you can lose that will not affect you much.