If the government is able to ban crypto currency because it's unnecessary and uses too much energy, couldn't they apply that logic to nearly any other modern luxury?
You don’t ban things you can tax with good results. Banning is for things you can’t tax. It’s a clumsy instrument.
of course, in my non-expert opinion, it would be preferable for the government to focus directly on the negative externalities rather than second or third order causes thereof.