It's easy to hedge an answer, but I'll risk being provocative (and I'm sure will be down voted despite the rules) and say: Yes it is a bubble. It exists because

It's easy to hedge an answer, but I'll risk being provocative (and I'm sure will be down voted despite the rules) and say: Yes it is a bubble. It exists because central banks have pushed interest rates too low which punishes savers. Those who don't want to incur debt to exploit the current environment are desperate for vehicles that will return them favorable results better than (real) inflation (not state reported CPI). It is easy to believe that the big banks are pocketing a lot of profits having this market mostly locked in. However, if you actually read the blogs of people who were documenting their experience with Prosper and P2P lending over the past 9 years or so, you'll find that because of defaults, the rate the big banks charge for unsecured credit is not that far off from what you need to charge people yourself if you hope to keep pace with inflation.