Countries that banned gambling wouldn't ban it for no reason. I believe that they have huge reasons for banning gambling in their country regardless of the huge taxes that they could get from it. Once they ban it, I don't think they aren't firm with their decision. Banning also has pros and cons in each country and I'm sure that the government focuses on the cons that made them ban it.
You can defiantly ban gambling in a country like placing ban on casinos and blocking online casinos but there is no way you can ban crypto gambling. The biggest pros of crypto gambling is that it opens window of gambling for people living in gambling restricted region. But the other side of this advantage is that kids under 18 years are also getting addicted of gambling. I would say crypto gambling has more side effects then good effects.