Just wait, within a year they will lose ownership of all these properties in bankruptcy and they'll be back in the hands of the city.
If anyone lent any money, it would be private investment- But those guys generally dont fuck around for sub 10mm deal size.
This is one dude using his own/biz's money/
However, they will likely have raised capital with some other portfolio of properties as collateral. So not all of this is coming from his savings.
I see others talk about how difficult it is to get a mortgage, etc. Let me just say from personal experience that it is not difficult to get a business loan (which is what this buyer will need, not a "mortgage"). Especially if he already has an established business.
You usually need a cash downpayment to even bid, and proof of funds in bank to participate.