All currency is made up. Even gold, or bitcoin, or giant rocks:
* https://en.wikipedia.org/wiki/Rai_stones
The only thing that has "inherent" value to humans is air/oxygen, shelter, water, and food. Everything else is psychological projection for convenience.
See The Power of Gold: The History of an Obsession by Bernstein:
* https://www.goodreads.com/book/show/249245.The_Power_of_Gold
* https://en.wikipedia.org/wiki/Peter_L._Bernstein
And Money: The True Story of a Made-Up Thing by Goldstein: