Or the banks own the most valuable, exclusive, world-changing IP in decades. Nobody else really has a shot at that IP besides a few other extremely-capitalized AI companies.

I'd loan them the money for that opportunity. It's possible that the IP will somehow turn out to be worthless; I don't know what will happen, but I am confident ruling out worthless. Could the lender could refuse Microsoft's payment - from a minority shareholder? OpenAI could accept Microsoft's money and pay the bank; with that offer, OpenAI would have leverage to play Microsoft and the lender against each other.

OpenAI could go bankrupt for many reasons having nothing to do with the value of their IP. For example, they could overinvest in developing it - a positive outcome for the lender.