This is one of the disadvantages of offline gambling: when you are gambling with those who are stronger than you and have the upper hand, you cannot just win them and quit gambling. They will make sure all that you have won from them is also won back from you, and you can also spend even extra, because they are not regulated and you can't make some kind of decision on your own, and if you disagree to play, there can be some kind of conflict.
I agree with you that on offline gambling we may not able to stop gambling when we want which we can do within a second on online gambling. The problem of mine not for strength but for one kind of request of few addicted gamblers. They tried to play as long as possible.
If your situation is not the one you wish for and you are forced to gamble against your wish based on the influence of those you are gambling against or you are with, then it's a bit of an easy decision to escape if you don't want to gamble again and they still insist since their own gambling urge has not been quenched.
The best I personally can do in that situation is to seat and wait without engaging in gambling again till they finish. It could be a hard decision to make, but it will be worth it if you can keep to it, as the rest of the money lost could have been saved.