The problem is that the actuarily "fair" price of these loans is very high because the risk of non-repayment is very high. If 25% of people don't pay back a loan, then you need an interest rate of at least 33% on the 75% who do pay you back in order to break even.

The only solutions are (a) to try to do a better job of identifying who will/won't pay you back or (b) to do more to make sure that people do pay you back.

(a) has the disadvantage that you aren't able to help a lot of people who most need the help. (b) can easily become exploitative as you increase the pressure on people who are at risk of defaulting on their loans.