I could think of a situation, that can be solidly backed.

You give them your bitcoin. They store it as a collateral. Like you get a loan for a house.

You have a certain liquidation price, where they have to either sell your bitcoin, or you have to post more bitcoin.

Then they earn money on your interest.

Of course, this can be PONZIFIED!!

Now you have 2 things:

- Decide if you want to use an overly collaterized loan for your benefit. If not, stop here.

- Find a way to tell apart the ponzified and overcollaterized loans. And use the good one.

My 5 sats.