I don't own any Bitcoin and never have, and am not especially fond of it. > Setting aside the non-trivial ecological damage caused by dams.. I don't think any

I don't own any Bitcoin and never have, and am not especially fond of it. > Setting aside the non-trivial ecological damage caused by dams.. I don't think anyone is claiming that the dams were built to mine Bitcoins. The power generation was provisioned to power towns, but it is generating more electricity than the towns can use or profitably transport away. > all that renewable energy could have been used to power something that actually adds value to society. There is a market to buy the energy. If anyone wanted it for basically any other purpose, the price would increase and the miners would presumably go anywhere else in the world with overprovisioned renewable energy, so that their profit can be preserved. Mining doesn't have many requirements: it doesn't even need to be on-grid. It's created an arbitrage market for cheap electricity, and people will search out the cheapest electricity in the world to use for it. By definition, the cheapest electricity will be the least wanted.