...I find it strange for people being able to beat the casino since this in theory it is totally impossible in the long run.
We should not deny the fact that there are professional players in this industry who, thanks to their card counting skills, regularly win at casinos. And this is the biggest expense item, and accordingly, the casino makes every effort to identify such players with a further ban on casino gaming.
I don't know if you've ever been to a real casino, where you are monitored 24/7 and you are not free to do anything, simply if you win too much you are out, either you cheat or not, you count cards or not, they catch you and throw you out, you can be the best card counter in the world but if you are inconvenient they cut you out
I have been in brick and mortar casinos before (not too many times though), but it is a open secret they have cameras on the ceiling of their gambling floor in order to monitor the activities of all card playing tables, and they indeed take note on whether a gambler is getting exceptionally lucky in their session against the house...
There is a good reason all physical casinos reserve the right to deny access to their facilities and games to any individual they want and without giving further explanation on the reason.
Depending on the casino and the size of their bankroll, winning too much in a consistent way (even though it is by pure luck) it would be enough for them to kick you out and told you never to step into their gambling floor again.
There are some documented cases about it, specially in casinos in Las Vegas.