Over the years, a lot of governments have outlawed offshore online gambling. They mainly do so by proxy, by making it illegal for banks or credit card providers to transfer money to unapproved gambling operations. In addition, to offer an alternative, most governments allow some kind of gambling to run in the country, but these are regulated and taxed.

I guess there are always ways to circumvent these government regulations and put your money in an online casino in Barbados or whereever but it takes a special kind of person to want to go through the hassle.

In very much the same way, governments could choke the flow of real money in and out of cryptocurrencies if they wanted to. They are probably planning to do so but it hasn't been on the top of their priorities just yet, the crypto bubble being more of an annoying mosquito than a threat to the economic stability. A government crackdown won't mean that crypto currencies will go away but it will be obvious to everyone that they'll forever be RPG play money, and only a small amount of enthusiasts will want to hold them. Prices will adjust accordingly.