> where the one who are supposed to refund banks will get the money?

Liquidating other assets. The point of the banks using SRTs is to push the default risk off of the bank and onto investors.

So now, instead of banks failing, private credit gets to bear the risk of the bubble popping. Since they can't sell the (now bad) AI debt, they will need to liquidate all of their other assets to pay the banks.

That's why a potential AI bubble burst can cause the markets to enter a death spiral and bring down a bunch of other, unrelated markets.

If private credit can't cover the losses by liquidating everything else, well, then they fail, and we either let it all crumble or do bailouts again.