Citation needed! Renewables are not free of externalities. Hydro damages environments.

Wasting renewable energy on crypto mining prevents that energy being used for something productive and so drives the need for more renewable capacity or drives further use of fossil fuels.

Bitcoin is an environmental disaster in the making. I see mining as akin to a religious rite that diverts potential away from useful activity and towards a fantasy instead.

It seems like someone along the way cleverly changed the valid and reasonable talking point about the intense and excessive energy use/costs away to a narrative Bitcoin (et al) are causing climate change - which is of course absurd; one of the bigger problems of Bitcoin (et al cryptocurrencies) is that their defence mechanism depends on using a higher amount of energy than someone who'd want to attempt 50%+1 attacks (or lower % take over attempts are still possible, just not guaranteed to allow double spend).