The vast majority of the loans were/are not serviced by the original lender. They are packaged together and sold in blocks to other investors. The junk loans were mixed in with the good loans and the revenue from the good was expected to cover the losses from the bad, averaging out.
Instead of the investors vetting these blocks of loans themselves, they outsourced it to the rating agencies. As a further attempt to mitigate their risk, they purchased CDOs which was a fancy insurance product that was completely unregulated.
The rating agencies were expected to look at the packages and assign a risk levels. Unfortunately the rating agencies didn't do their job and over-rated the packaged loans. They too were also operating in the false world where real estate doesn't ever loose value.
Just to spice things up, Freddie and Frannie didn't have to follow industry normal standards of maintaining an appropriate cushion of cash to stand behind the guarantees they had outstanding. This is where the implied support of the US taxpayer came into play.
The loan originators flipped the loans a fast as possible and made their 1% or so origination fee. They had no risk. They made their money at the front of the transaction. They just had to get the paperwork filled out right.
The secondary marketplace attempted to cover their risk with ratings and insurance. They re-bundled the loan packages and resold them, thus complicating the picture more, but also generating transaction income.
Freddie and Frannie operated without concern of risk, Congress had their backs, especially Barny Franks.
AGI and other created CDOs out of thin-air and sold them without regard to reserves to back them up.
Where was the risk in the system.
- The original borrower of the individual loans carry
- Reputation risk of the managers of the various companies involved
- Tax payers of the world and their grand-children, since our economies are all so intertwined.
By bailing out the 'to large to fail' banks and AIG, the governments have introduced so much moral hazard that it will likely take years to recover just that. These companies should have been allowed to fail and the executives that were involved in the decisions banned from the industry. The regulators that approved the mergers that generated these huge companies should loose their jobs and banned from the industry. It wasn't so much a lack of regulation, but a lack of using existing regulation that allowed these huge companies to come into existence.
By doing all these bail-outs of the banks, AIG, even GM and Chrysler the clear signal has been sent that the government has mulligans to hand-out and everybody gets to keep their jobs and reputations.