Because they have utility? Making beanie babies while wasting more and more energy is just that, wasting energy and destroying the world for nothing.
If one pays a fair price for power then nobody has a right to say how/what/where they can use that power. And to say that Bitcoin is destroying thr world for nothing is just pathetic.
And I think you'll find that free online porn is far more detrimental to soceity than Bitcoin ever could be.
Anyway, proves how much you know about electricity and Bitcoin. At least 70% is from wasted/stranded energy. It's a win-win for everyone involved. Bitcoin is also helping to draft new ways to use and hardness excess energy including portable mining rigs that take the gas from fracking and turns it into money. That gas if not used is flared as it's a liability. Another win-win for all involved.
As for the long, tired arguments of the Bitcoin bears - too much electricty, what happens when the internet goes down, governments will surely ban it, nobody is using it, can't buy a cup of coffee and so on. By all means come up with arguments against Bitcoin but try to use some novel ones, not the same old tired points that have been used for years and have been debunked time and time again.