To the sibling, while I largely agree, I think there's some argument that building out additional manufacturing capacity for renewables even if it goes towards crypto mining has beneficial knock on effects for reducing the cost of the equipment provided that the learning curve effect and economies of scale outweigh the competition for resources, which to be fair isn't guaranteed.
It's mainly the fact that Bitcoin mining sets a price floor on electricity prices. It's a buyer of last resort. Without it you'll get negative electricity prices and less investment in renewables.
