Ethereum will use around 99.95% less energy post merge
Proof of Stake is already how our current financial system works. The people with the most money make the decisions. Proof-of-Work is provably resistant to this, as evidenced by the 2017 blocksize debate where almost every large miner and bitcoin company wanted to change the protocol and it was fought off through grassroots efforts. A PoS currency will be controlled by a cabal of US financial institutions, and indirectly by the US regulatory system. Be careful what you wish for.