No, money is not a “collective illusion” or more often called a “collective delusion.” How many times does Saifedean have to address this one for people to learn…

Fairly certain that idea is not from Menger (maybe a misreading of Menger), but more likely Keynes and it’s a socialist idea, not an Austrian one.

You don’t just arbitrarily decide that one money is better than another and then the market uses it successfully based on delusion. Rather, the marketplace, over time, organically determines the best money based upon monetary properties (scarcity, durability, portability, etc.)