Loan companies don’t need every borrower to repay. They need enough borrowers to repay, and they need to manage the resulting losses well enough to remain profitable. Lending is a business of pricing and managing risk. They’re not betting that everyone will repay, they already know some people won’t pay, so they have to do something about that - steep interests. They charge steep interests, allowing them to earn more than the amount originally lent. However, interest income is only profitable when it is sufficient to cover defaults and other costs. For that reason, they set interest rates pricing in the risk of nonpayment in mind so the interest earned from borrowers who repay helps offset losses from those who do not. From their latest financial disclosure, it looks like they’re managing it pretty well.