Difficulty itself is intersubjective too. Bitcoin objectively does not require any energy to run. These are the rules that we agreed on.
However I do agree that these intersubjective rules anchor Bitcoin in objective reality.
Discussion
> Difficulty itself is intersubjective too. Bitcoin objectively does not require any energy to run.
No energy required means a system that is easily overwhelmed by an attacker. PoW is an essential part of a decentralized network security.
It's the most resilient system we currently have to hold, receive and transfer value without involving 3rd parties including the state itself.