Debt would be a tiny fraction of equity and tiny fraction of base money in an equity-based system with finite money. Interest to pay loans would come from the borrower's success at deploying that loan productively. In cases where they cannot pay back, they default. So lenders' interest basically comes indirectly from those who lent and got defaulted on. In a debt-based system, debt levels are pretty high relative to equity, and extremely high relative to base money. Even a rather small default wave is a pretty big percentage of the monetary base, which is why they don't allow it for long and instead print more money.