We have a luck as long as we are still alive. It can come out sometimes like in gambling and we can win something but luck doesn't last long so we must learn how to quit before it ends.
I think you are missing something by saying, "We have luck as long as we are still alive," but you are right that it does not last long. Also, know that luck is just an expression when someone is being lucky, not that anyone possesses it whatsoever. It is just an expression to qualify the narrow escape or opportunity/chance that was visible in an event. In gambling, no reasonable gambler will ever think of luck, though they need it, they should rather think of a working vice and plan.
Talking about when we have to stop before the luck ends will not be easy and will tempt us to continue playing because we think that luck is still on our side so we have to use it to play. But no one knows when the luck will end and when we lose in one round, we still think this is just a coincidence and we will definitely win the next round. But when we lose again, it also doesn't make us stop and instead continues to play, making us lose the winning money we got earlier.