If CPS's loans were profitable they wouldn't be dumping them on unsuspecting Prosper lenders.
On the terms CPS is getting, heck yes they would.
It seems like they're selling loans issued at 19% for 15%... meaning the Prosper lender assumes 100% of the risk, CPS keeps the lien on the vehicle, and CPS makes 4% off of Other People's Money.
Even if CPS knew the loan to be "close to a sure thing", they should just take the Prosper lender's money, originate another "close to a sure thing", and then keep the extra 4% made from the first loan. If one goes south, well, sucks to be the guy who is actually risking capital.