Now I am imagining a world where profit doesn't stop.
Like all the money gets centralised more and more until everything is owned by a single tiny group or even one person. They literally have all the money in the world.
And everyone else just ... stops using this money, since there is no point. Then they start using a different form of currency like pearls because that is the only way now to trade between non-owning people. Making all this money completely useless.