This is a naive viewpoint. Ethereum (as a currency) is an "M0" token, like cash or Fed deposits. There's a lot of handwaving about bonds and whatnot, but essentially the Fed can create new money simply by changing numbers on a balance sheet, and they can make that money into folding money and change which they can issue.
The banking system is a complex system that creates IOUs on top of that base. Some of those IOUs are even better than the cash layer -- you can't buy stock, for example, for cash, you need bank IOUs to do that.
That said, then, what is PoW and PoS used for? They're essentially distributed methods of ensuring that nobody can forge money. So the equivalent in the world of dollars is not a bunch of bankers chuckling to themselves about how they're fleecing the plebes. The equivalent in the real world is a bunch of aircraft carriers and planes and bombs and people with big guns, which gives the ability to say (credibly) that it is a crime to forge dollars no matter who you are or where you live.
