> How is specialized mining hardware an environmental disaster?
The harsh judgement that it is an environmental disaster rests on these points:
1. The network does a little bookkeeping work, but around 1 billion times less efficient than necessary, just to achieve the defining characteristic of crypto, "trustlessness" or the lack of a central authority.
2. The incentive system is such that by design and ineluctably around one third or so of mining rewards will be wasted on electricity and electro waste.
Other industries work hard to minimise their energy waste, and often impressively successfully, by the way. Bitcoin mining cannot.
(Note: Bitcoin could become 99% more energy efficient overnight (plus minus two weeks), of course, if all the mining pools banded together and took 99% of their hash power offline. After the next difficulty adjustment, BTC would be exactly the same, but waste 99% less energy. If only this coordination problem could be solved, maybe with some kind of ... central authority?)