Well, a credit history tells you whether a borrower paid his credit card bill last month, not if he is going to have a job next month. My point is not that people will try to run away with your money, but that holding 100+ notes from Lending Club might not be the diversified investment it appears to be, especially when some macro event happens.

Peer to peer lending being somewhat new, I would say some of the borrowers think it's cool. Some of them might also be making a principled choice ("banks are evil"). But ultimately, if you have a reasonnably good credit profile it should be noticeably cheaper than the average traditional lender with its branch network etc.