All money is, and has ever been, is a promise that you did something for society. In the olden days of tiny villages, it'd be "he's the guy who digs the latrines, give him some carrots.", in the modern era, it's "here is some dollar bills, which imply this guy dug the latrines and was given them as a sign of work completion since society is too big to know everyone personally, give him some carrots."

Even when gold was money, money was just trust. Gold represented a value of barter, you traded someone your carrots, they gave you gold representing the value of the carrots to trade with someone else, instead of giving you the barter directly in return.

Trust, or less charitably Blind Faith, is the only thing that keeps the economy alive.