Everything is producing different kinds of waste: factories, nature (during any cataclysms), or even cows when they fart (and by the way cows have 2nd largest population among mammals and their fart is really harmful). If people give up mining BTC it doesn't mean that everyone will invest their money into some green stuff and start planting some trees.
If people stop mining cryptocurrencies they can start using even more harmful technologies.
but most of the mining is coal-powered[3] and the fact that we're increasing the stress on the increasing need for sustainable practices - or, rather, the magnitude of the stress itself - is staggering.
People can use nuclear energy. It produces less waste.