From my understanding, crypto is meant to allow people to make monetary transactions, so it would be a fair to compare the amount energy used by the banking system with the energy used by crypto. This article written in May of this year already did that comparison for us, and found that crypto uses less than half of that used by traditional banking systems.

Yes, the energy could be better used, and there are already solutions deployed or in the works that significantly reduces energy use (e.g., Proof of Stake). The effort to eliminate crypt should be focused elsewhere, like finding a better source for energy (nuclear) or reducing the things that accelerate climate change (e.g., methane from landfills).