We can't expect more in winning rather than of losing cause if that will happens, those casinos will never exist any longer. The real thing about in gambling is not of winning but to lose but of course, if you have luck in gambling you probably have a huge chance of winning than of the others who never have.
With the huge numbers of gamblers, I may think that 30% may win and this is why casino's and any gambling site will survive for many years.