Well imagine if there is only $55 worth of currency in circulation. Or better yet only $52. The lender ends up with all the currency in the end (and maybe some that does not exist yet). The response is that currency is printed. If the production of society increases at the same rate as interest, then there is no problem, but that is rarely the case. This is why there is more debt than money in the world. Currencies are then deliberately debased in order to pay back debt quicker.

https://www.cato.org/policy-report/julyaugust-2011/deficits-...

(I realise limiting the money in circulation to $52 is an absurd formulation, but using these crazy limits helps understand the larger system)

The difference between real growth and the amount of currency is the "metabolism" I referred to earlier.