I think that threshold of loss various between gambler to gambler, it depends from his income ecc. About me, there isn't a threshold of loss, when I start to realize that I'm losing too much, I leave casino and go to have a walk, and will come to play in another day.
That should be.
I think that's how most players do it, responsible. Either they have a pre-established threshold that they don't exceed, or maybe they exceed it a little but they are able to stop, leave and come back another day with a fresh mind to try their luck.
The problem is the problem gamblers, who don't stop at the limits and end up losing much more than they should.