As long as they desire not to feel that "remorse" anymore and don't want to gamble anymore, regret is what they do and they really won't come close to gambling even if they are invited to gamble by their friends. But if the "remorse" only occurs when they are done gambling because they have suffered a loss but still want to return to gambling, it is not truly remorse coming from their heart. It's just a regret for having lost the money they used to gamble and they will try to do better next time. But the next opportunity probably wouldn't change the outcome, so they better consider accepting it.
I agree that if you feel remorse even just once, that's going to change your whole approach to gambling without a doubt, I get that it may not be a huge deal right away but at the very least you would know that you are doing a good job with what you have and that should make you feel proud. Being able to quit gambling is a tough thing, but even gambling less or gambling with a strategy and limitations is hard too, and after feeling remorse you start to do that.
For example, no matter how much I want to gamble, no matter what I am feeling, no matter how happy or excited or angry whatever I am feeling, if I reached my limit for the day, I stop gambling and do not gamble more at all, that's just how it is for me, try to do that.