The problem with bitcoin, or the issue to be more honest because it is not really a problem, is that right now there is no "better" use for that electricity than bitcoin. That is the truth you must grapple with. Or as Google would say, the best option for the collection of arguably the most brilliant minds that have ever walked this planet is to work for Google, trying to get people to click more on ads. That that is true, that is your problem and everything else is noise. If you really want an environmental problem to tackle go fight the oil industry killing thousands of animals every day, destroying communities every day, destroying them literally.
But, if you insist you must "fix" something about the current crypto boom because somehow they do not adhere to your morality then you should look at everything else but bitcoin and ask yourself, why is the thing I consider moral not attractive to the market?, what can we do differently to make doing something else at least as profitable as mining bitcoin? If you just tax it or try to ban it they'll just move and you'll be a)poorer and b)left without a say.