2 exceptions to what you said.
- Whatever money raised through IPOs and other public investment is mostly the general public's saving accounts. So far it's just $80bn in the SpaceX IPO and $40bn from the bond issue they did shortly after.
- Just like the mortgage crisis it's the banks holding the debt that's been issued. Now since 2008 they were meant to firewall between their retail banking arms and their investment arms so that if they fucked up again the retail banks were safe. However this legislation got repealed in the US, so we could be looking at a bank bailout again to make sure the banking system doesn't collapse with everybody's money in it.
The money loaned still exists, you're right. Trouble is it's not in the AI companies anymore. It's been spent. It's gone through them out to other companies (like Nvidia, MS Azure, AWS, Google Cloud, etc).