All money is an entirely human construct where we put value on things.

The most significant assumption is that fiat money is backed by the the nation state issuing it as MoE to its captive citizenry and is backed by the nation state. What is the nation state? Nothing more than an abstract human construct!

Bitcoins value is in the global voluntary community of association that it has built. There is zero compulsion or use of coercion.

Some of us put real value on this voluntary structure where all participants in the protocol are treated equally without fear or favour and without anyone enjoying exceptional privileges or advantage over others... Compared to the structure of fiat money that is inherently hierarchical, mostly issued as debt obligation, giving bankers and governments significant privilege and advantage over all other participants.