I'm guessing it works because of the (relatively) small amounts of money involved. A years savings ($1000-20,000 depending on the sou sou) is not worth pissing

I'm guessing it works because of the (relatively) small amounts of money involved. A years savings ($1000-20,000 depending on the sou sou) is not worth pissing off your entire social network over. The real value wouldn't be the finance, but that the group dynamic would encourage commitment to savings. I'm guessing these people would generally not really need loans, they want a bank that will publicly scold them if they're late with their monthly savings deposit. They get a big, useful chunk of money to make a major purchase (or deposit on a real loan), and get the community pressure to save for it. FTA - a "sou sou" is basically a group savings system - everyone puts money in the pot and once a month one group gets to take out the lot (often based on needs / goals / whatever the organiser thinks). Technically the first family to get the take would be advantaged (since it's basically a zero interest loan for them) but it's a relatively small amount (interest on a year's saving) so it's not like the others are getting massively stiffed (compared to what they'd get leaving money in a retail savings account at 1% interest minus fees or whatever it is right now).