BurtW, to answer your question, fraud is always a concern. But, we do not get a lot of incidences of people, who pay with stolen credit cards or hacked PayPal accounts. We are very good at screening all of them out. We do have some incidences of "friendly fraud," people who use their own card, but then fraudulently report the payment as unauthorized to their credit card company.
We use third party consumer data vendors and blacklist databases to screen for friendly fraud risks. We have also developed effective procedures for disputing chargebacks with credit card companies and have a good win rate.
Our investors do not lose money. Average profit margins (their interest fees less chargebacks) are usually 80%+, which we think is very good.
We also have a profit margin guarantee for our investors. If their profit margin drops below 50%, we pay for their chargebacks! We offer it, because we are confident in our ability to keep the fraud percentage low.