or, of winning a significant, more than 50%, addition to their bankroll, to be more precise
Oh, did I read you right?
It seems that now you no longer claim that it is impossible to consistently win from a casino (provided the latter stays provably fair in the process, of course). It is just that your winnings won't be that great. And most importantly, it requires a totally insane amount of patience and focus, which addictive gamblers simply lack for pretty obvious reasons (because so much patience requires a truly conscious effort on the gambler's part, i.e. not emotion)
Man, I never claimed it was impossible. Quite the contrary, I claimed that with billions of gamblers it is possible, for some of them, probably for just one in ten million, to win big amounts, consistently, year after year.
But that's not where compulsive gamblers should look at. It's pretty stupid to think that you can be one of those extremely lucky ones. Rather one should concentrate on what happens to most of the people.