I have made some findings about this before if I remember correctly. There are people that have sued gambling sites before but the result has always been the gambling site winning the lawsuit. So just know that if anyone sue any reputed gambling site, the gambling site may win the case.
Casinos won't allow a Sue to work out against them that's because it will not only tarnish their business image but also reduce their reputation and that you are affect the ability for them to be able to get new customers especially if they lost the case.
It's the same reason you find out that casinos try as much as possible to have good customer support just to ensure they have a proper relationship with their customers else they could risk losing them.