Yunus in Bangladesh has proven the default rate among these small borrowers tends to be really, really low. 98% of those who borrow pay back. That is a much better rate than rich people and corporations in New York City. Their default rate is higher.
So what gives? Why were mad men bankers pouring trillions into real estate and shady finance tools a few years back instead of pumping that money into microfinance? Stupidity. Racism.
You can't build enough schools and colleges and print enough textbooks on time. But you can hope to take everyone online. Similarly microfinance has to be taken to all those people. Microfinance is the ultimate fishing net.