none of those details justify egregious waste of power
This argument was (and still is) valid for PoW algorithms, but energy consumption is now barely a factor for Ethereum, which is the main network we take payments on [1].
Ethereum is currently doing 30 TPS [0], and Paypal ~200 [1]. Assuming that energy usage scales linearly (a naive assumption, but for arguments sake), it could deliver similar value with 10x lower energy consumption, I don't find arguing against the adoption of PoS crypto solely based on sustainability very credible either.
[1] https://www.ing.uc.cl/en/boletines/engineering-student-scale....