> Every single dollar was created from thin air, as a "loan"
Not quite. Minted currency isn’t created from a loan. Neither is fiscal spending.
On the other side of the spectrum, money is destroyed through taxation (by the state) and repayment of debts and defaults (privately).
The monetary hypothesis of income inequality is overly simplistic. It supposes our tax, trade and funding policies are all dictated by monetary policy, which is obviously nonsense. (That or our tax, trade and social spending policies have no effect on inequality. Which is obviously stupid.)
It is an easily-digested hypothesis. We like those, particularly when the alternative is reading lots of arcane monetary financial texts.