I think the most important thing is to stay calm. Second, do not think about the loss. If you think about the money you lost, unhappiness increases and the person starts to suffer psychologically.
It's hard to implement these things for a gambler.
First, it's hard to stay calm especially if the money that you used for gambling and lost was intended for a more important thing like expenses or paying bills.
Second, not thinking about the loss is also hard. Unless you're a rich man who doesn't care about losing money in gambling, there will be a point in their life where they will think about the losses.
Well, these are just temporary emotions and at some point, you will just move on and move forward and make better decisions. Those who will not move on from these emotions will lead to stress then anxiety and they will be depressed.
A person should gamble with money that they will not be upset about losing, but this situation may change over time.
If they are not going to gamble again, they may definitely need to see a psychologist.
Because gambling is a kind of disease.
In investing, we always say "Invest what we can afford to lose" but we know that this is hard to do especially if we feel that we can make a lot of money by investing into crypto, there will be a time where we are forced to invest money that we can't afford to lose just to chase those potential profits. It's the same with gambling. Sometimes, we tend to spend money that we can't afford to lose because we chase those profits that we might get.
As for gambling is a disease, it would be better to elaborate this even further.