One aspect I must mention is Bitcoin miners flock to where energy is cheapest for them, not taking into account negative externalities. This is why you see miners attacking CI services to try to use them for mining crypto: free energy is the best deal, even if it is costly to someone else: https://drewdevault.com/2021/04/26/Cryptocurrency-is-a-disas...

Of course, the climate crisis is caused in large part by capitalism failing to deal with negative externalities, so one could argue that Bitcoin is just another facet of our corrupt system privatizing benefits and making the public bear the costs. But nevertheless this is a fundamental flaw in arguments that Bitcoin miners only farm where energy is "cheapest".

As for why it's a scam, it's hard to summarize, but I'll try: cryptocurrency is not currency, not decentralized, and not private. https://jacobin.com/2022/01/cryptocurrency-scam-blockchain-b...