Just because there’s “no better” use for that electricity (which I disagree), does not justify using it up on bitcoin mining. This is like saying it’s morally permissible to do A because if you don’t, someone else will.
Not to mention conflating “the best use of X people’s time” with “who is giving out the best compensation in a society where we need money”.
The mainstream view -is- positive of Bitcoin. Very few people are actually concerned with the environmental impact.