I think it's not just about control but more about how someone can understand it and also maintain awareness of the dangers of the risks that lurk, because that way I believe that it is unlikely for them to lose control or get caught up and carried away by the situation.
Yes, I grabbed a whole lot of sense from what you just said, and it's true what this individual may be lacking is self-control, because for the fact that the person O.P is referring to became addicted to gambling due to the fact that he was working in a casino, is a clear sign that that's the same way he would have continued gambling if he wasn't working in a casino. Because thou the environment a person finds himself may have influenced on a man, so for me, I think this guy was already into gambling before they got a casino good.