Science? Cardano published 100+ scientific papers https://iohk.io/en/research/library if you have time check out the ones about Ouroboros (proof of stake)
As the amount of commerce on bitcoin increases, it becomes more desirable to reverse transactions, so there is indeed some ratio of "GDP to energy expenditure" that needs to be maintained for a sufficient level of network security.
So yeah it doesn't need constantly increasing energy expenditure as long as the amount of commerce using bitcoin stops increasing.
New coins will come along with greenwash in their rhetoric but ultimately you have to trust the science.
It's funny how everyone trusts the science when it supports their worldview and ignore it when it doesn't.