as to which I can wait 3-5 years or more for a full return. I would keep those dollars segregated and as cash came in from the first crop of loans keep re-lending them in Prosper (or LendingClub if you want) to others to compound return and diversify risk within the pool of your Prosper loans.

I would not do a deal like Prosper with cash that I might need in the short run. Nor would I do it as a one-off deal where I do one or two or three loans and just wait for maturity. I'm sure good arguments exist against my approach, but that would be my approach.

I would keep up that approach until I was ready to exit for some reason.