Whether you like it or not, human beings find a need to store value. In countries without a proper store of value -- due to e.g. government intervention -- they start hoarding commodities (e.g. wheat, cotton) or productive assets like cars.
So the question becomes whether having something like Bitcoin as a replacement for hoarding useful assets is actually environmentally preferable. Hoarding millions of cars as a store of value -- as they do in e.g. Argentina -- also impacts the environment, as we need to produce more cars to account for it. So if hoarding bitcoins replaces this practice, perhaps it will become a net benefit for the environment.
Of course, this point of view assumes the inevitability of hoarding. As far as I can see, it's a survival instinct, which cannot be suppressed -- we can only control which goods are hoarded. Ban money and people will start hoarding less saleable goods.