[iguy]

My point is that a theory that says their business practices follow from moral failings doesn't explain anything about the world. Some businesses just mysteriously seem to always be run by bad people.

Conversely, assuming that every businessman is about equally greedy forces you to look elsewhere. Their loans are almost by definition high-risk, that's why they are expensive. Low-risk borrowers are a different market.

The fact that we can learn something by thinking about their business does not mean anything like "defending". It's just that sometimes the lessons are clearest with extreme examples. We can learn interesting things from studying drug gangs, pirates, kidnapping schemes, too.

We can also ask questions about whether the world would be made better by prohibiting loansharking, and I actually don't know enough to have an opinion. But it's clear to many that prohibiting drug-dealing has had some nasty side-effects.