Ah, ok, so this is more like a thing where you drive around looking for loose change on the ground, and you find enough to exceed your fuel and maintenance expenses. But you can't scale it up by hiring more drivers, because there is only so much loose change to be found.

Surely you see how even a 10% safe return on investment like these DeFi schemes offer is a whole different thing, when it's a compounding return. There's no way to sustain it. All the arbitrage opportunities in the world can't deliver the funds required to make investors' money grow exponentially.