I guess you would not stop someone if they are enjoying, the scenario of what OP is trying to convey to us is if we are seeing a gambler who are losing control and just gamble everything he has even if he is losing as we already know how a situation would end up.
I've been in that kind of situation so I totally understand, I gambled while I'm drunk so I got more aggressive and wasn't thinking straight and end up losing everything, including the money that was suppose for family expenses or budget.
I think I will only do that to a very close friend, and if I really do see that he is not thinking straight.
But otherwise, I won't interrupt someone else's game. They are already adults to know their decisions.
That is their life and hard to intervene someone else's life. You can't just barge and suggest something to them.
They will have their realizations at their own time. So don't force it to others that you barely know.
They'll only realize once they ran out of money, that's the principle of most gamblers, they stop when they have nothing left but if they win, they want to win a lot of money, that's why we got caught up by our bad luck as we are too greedy, too greedy to stop and just bag a win and to greedy to stop that we can't accept our loses easily.
In the end, we will realize the hard way, and it will already cause us a lot, would be okay if we not reach into the situation that we have to borrow money just to gamble as that could probably hurt us more in the future.