Great question, OP.
Is it possible to work in a bar and not drink alcohol?
Is it possible to work in a cigarette factory and not smoke?
The answer is always yes and many people manage to do that.
If your friend has a problem staying away from gambling and his casino work is leading him astray, he should find another job.
Yes, this is actually true because we do know that each person would really be having their own levels on how they would really be controlling themselves in speaking about on the things
that they are really that dealing with. Doesnt matter if that particular thing is in front of you or you are working into or not, it will really be just that depending into someones control because if you do find yourself having no control and would really be that wanting or liking to deal with the things on what you are current working on, then high chances that you would really be doing the same and this is would really be that just normal. This is why it would really be that important that you should really be that wary on the things that you've been into because not all would really be having such control.
If the things faced are still something reasonable to do in the sense that they do not have the potential for bad impacts in the future, then yes, it is okay to make a decision to engage in the activity, but if it turns out that from a rational point of view it is indeed something that can be dangerous, then clearly taking precautions will always be much better than regretting it when it is too late.
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.