You don't make loans to people unless you have evidence that they can and will pay it back. BTCJam for example has reputation scores, and people actually say what they intend to use the money for.

The default rate on BTCJam, which was one of the first loan services is 10%, this doesn't compare well with mainstream rates however, Bitlendingclub is supposedly one third of that, which compares favourably to mainstream rates https://fred.stlouisfed.org/series/DRCLACBS