Money is just belief.
True - from a philosophical perspective.
But if you are engaged in monetary design it helps to have a systems analytical appraisal at your disposal in addition to mere philosophical observations.
No, really. It isn't just philosophical. It is purely economical. Money is nothing else but a belief that others believe in value - and as such, one is part one-self of the group of believers that others believe in. And that's all money needs: a self-sustaining community of people who mutually believe in each-others' belief in the value of the asset, the belief in the legit creation and the belief in the absence of double spending (conservation of money in transactions).