In order to regulate digital currencies in relations to cryptocurrencies, the government must and should be the majority holders of all cryptocurrencies. With this, they can control the amount of a particular coin circulating. They can determine the market price of the coin at a particular time and period. IF the government can achieve this, they can regulate the crypto market and world.
you don't regulate things by having a stake in them! it is like saying for the government to regulate companies like Apple, Microsoft, Google, Dell,... they have to own majority of the shares of these companies to control them! which is obviously not the case.
in a society when the law maker makes a new law the law enforcement enforces it. they don't need stakes to enforce it. and cryptocurrencies and their regulation doesn't have to be any different than regulating a company.