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Top casinos that you can find here don't have limits. That's what I've seen so far. Small casinos usually have limits because they have limited amount of bankroll. I believe this is better rather than offering no limits but can't pay their winning bettors.
In practice, it is indeed better for us as gamblers because we can see such casinos are operating with a clear mindset and keeping the size of their bankroll in mind when comes to paying possible wins to their gamblers. But in the side of the casino, it may not be as attractive for them to limit wins, since that would turn whales away.
In the end, small casinos need to have as much volume as possible, even if such volume comes from rush gamblers, so some of those casinos risk it and welcome gamblers who may even have more money than the house.
That is quite and weird situation to be in, as a casino owner, if you ask me.
Casinos then need to opt to keep an equilibrium, between their bankroll and the money they can offer as maximum win, which need to be attractive not to turn people away.