It's an outcome of the way money is structured.

Debtors borrow. They get money and spend it. The person holding the money gets paid to not return it (interest). It's like the system is maximally stupid and designed to exacerbate wealth inequality.

The fungibility argument is bullshit here and just serves to obscure. Let's say 10% of money holders refuse to return the money, then 10% of borrowers are screwed. The borrowers can play a game of musical chairs to "decide" who is going to get screwed, but it doesn't change that 10% get screwed.

Oh and the best part? You can't escape money, because it's like a public utility and even if you come up with an alternative, you'll still have to pay taxes, in money. Meaning that money is not just a monopoly, it's inescapable.