I think it's difficult and what if there is a trick in the loan.
but of course to make a loan there must be strict rules about collateral if the debt cannot be paid.
Even this forum have lending section, some people, to not name them or advertise them, are earning bitcoins with lending business from a long time. You even have some sites for that, I remember poloniex, among all other exchanges, also had lending option. It`s nothing new, people earn like that, you need to have bankroll and skills to do it. You can`t lend without collateral, you need to have good rates, better than others. Eventually all debts are paid if you are careful and take all necessary steps.