The business case is that people will buy their tokens/invest on their platform which will increase in value which will cause more people to buy in etc. If you look closely enough just about every successful blockchain project is a ponzi scheme on some level.
As far as I can tell, any defi project that isn’t an outright scam is just providing credit to people to speculate on cryptocurrencies. I’d be curious to see any counter examples. Otherwise it’s just turtles all the way down.
> providing credit to people to speculate on cryptocurrencies ... turtles
People do use it for leverage but who cares. It doesn't undermine the contracts, and certainly doesn't make the concept worthless. You can securely lend/borrow stablecoins globally with zero middlemen. What you do with the credit/interest is your own business.
