PoW energy consumption is an Achilles’ heel.
In case of Reddit cataclysm? …
PoW requires an enormous amount of electricity and specialized hardware.
It is not very decentralized, and PoW is an easy target for nation states to attack. 70% of Bitcoin mining takes place in China. China is in control.
When Bitcoin was small and you could run a miner in a closet, PoW was fine. Now it needs as many power plants as the country of Chile.
There is no way PoW is sustainable and won’t be a target of nation states.