If they know that they can not win from the casino, they will choose not to playing gambling. If they work in a casino because to meet their needs, they should focus with their work and not trying to playing gambling. Even they already see how people lose control in a casino and makes the employee hard to control those who becomes mad and ruins something in that casino. That should makes them not spends their salary just to make more money because that will not easy for them so they better to saves their salary for their needs.
It depends on how those people can hold themselves by not playing gambling in casino and understand the effects that they can get from gambling. So they will not trying to playing gambling when that just give a bad effect to them.
In some casinos, the rules explicitly prohibit employees from playing in other gaming establishments. And this is understandable, if a casino employee, after finishing work, goes across the street and continues to place bets, instead of resting and then the next day comes to his main place of work sleepy, then this can entail large losses for the casino.