TPTB,

Fundamentally, currency is about trust and consensus: A sufficient amount of people perceive value by proxy in a token.

Regardless of how truth is constructed and protected, it's the consensus part that matters. While the implementation may or may not be decentralised, it's the decentralisation of POWER that's interesting.

As you say, it may very well be a delusion. All currencies are delusions. It's just that we all agree on the value of the collective delusion.