I don’t know how it would work in North Korea, but I think an easy solution would be to use the Tor browser. Is that allowed, though? By “allowed,” I mean: can a person download the Tor app and use it to access online casinos or browse other websites? Or is that also forbidden by the North Korean government? Because when you combine Tor and cryptocurrencies, you basically have total freedom anywhere.
People from North Korea do not have access to the normal internet in the same way people like you and me have. Their internet is closed and only are allowed to access specific webpages made by the government, only people within the political elite of the country have access to world wide web, the rest cannot. North Koreans are probably pushed into a situation in which they're forced not to gamble at all or risk time in prison by gambling underground.
It could be possible as well that there are some underground casinos which are run by people within the elite of the politic lower there, it is a corrupt country after all.
Haven't you ever wondered why we do not see people from North Korea all around the internet in the same way we see South Koreans?
It used to be the same way in Cuba, but now people have internet access in the island, so they can gamble on online casinos and use cryptocurrency.