It’s true that all money is made up, but not in the same sense OP means.

Like I could give you 20 dollars and it’s made up in a sense, it’s just a piece of paper, but also you can go to the store and buy things with it.

Whereas if you’re an investor in a company and the CEO does some self dealing which nominally values your shares at 20 million, you can’t go spend that. It’s even more made up