Of course not everyone does the same thing even though they work at a casino, because I think maybe some of them who work there already know the rules that they are only unlikely to win so they don't need to think twice about this they choose not to gamble, besides I think everyone is not happy with gambling maybe some of them work at a casino just to meet their needs so they do nothing more than work.
Although maybe that makes them unable to resist gambling but I'm sure there are people who don't gamble even though they work at a casino, it's just that maybe the number is very small compared to people who gamble. Besides I don't think the casino requires its workers to spend their salaries at the casino where they work, that's ridiculous.