When I inquired from the attendant, she said he was a regular customer and that he usually raised money for gambling through the manual jobs he does around the area. She also told me that he has never misbehaved and acted violently in the gambling house so she was comfortable with him.
My question now is are there any moral, ethical or legal obligation to bar a person from gambling after physically observing that he is mentally unstable?
That's discrimination the attendant already said that he never misbehaved or caused any trouble so he has the privilege to play unless that physical casino has a rule barring people with unusual behavior from staying on their premises but then again they have to check the background and examine the person because looks can be deceiving.
When it comes online, there's nothing in their terms that will tell gamblers to submit their mental or health condition, it's up to gamblers to examine themselves if they are fit to play online, when it comes to gambling it's always been played at your own risk.
Yes, gambling is a great source of entertainment but it can also become a source of mental anguish, so examine yourself if you can take all the risk in gambling.