- mining metal for coins of fiat currency
- mining gold because people don't trust fiat (digging otherwise useless-in-that-quantity rocks out of the earth, a Proof of... hmm... WORK?)
- running stock exchanges because people don't trust gold either (tungsten has almost the same density)
- smelting the plain metal and gold
- the US military which backs the dollar, and the other armies which compete with it
- manufacturing paper for fiat (lots of water consumption?)
- printing fiat
- transporting fiat
- transporting bank employees
- building shiny glass palaces for banks to signal their status (PoW)
- flying bank managers across the planet to signal status (PoW)
- the office equipment, servers, and employees of banks
- existing fiat currency becoming garbage due to wear, better fakes, and inflation
- the network of hundreds of thousands of ATMs and the COBOL mainframes which back them