Of course every industry has customers who run away, but the risk for the moneylending business compared to other industries has got to be at least 20x greater. Hence if you say set up a seafood trading business and out of 100 customers that you have, 1 runs away without paying you, you have to expect that the number for your moneylending business has to be at least 20 out of 100.
Think about it. Someone who buys seafood from you is either reselling it or cooking it as his business. His intention is to do his business and make money. He may fail or he may succeed, but his intention is to do business.
Now consider someone who borrows money from you on an unsecured basis. You have to ask yourself. Why does he need money? Why does he need to borrow money? Why does he need to borrow from you?