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.
Honestly, I don't know whether the person in question was involved in gambling before he worked at the casino or not, but what is certain for me and in my opinion, no matter what, the point is that the environment and atmosphere in the casino can really make someone who doesn't gamble become an addicted gambler, especially when they can't control themselves and also when they don't understand the fact that the casino will always be the superior party.
And on the other hand, maybe your opinion could also be right that the person might have been involved in gambling before he worked at the casino, and the point is for me, whoever you are, regardless of whether you are a casino worker or not, I think it is unlikely for you not to have self-control along with some other limitations when you do have a true understanding of what and how the chances of winning and the risks actually are.