The Consumer Financial Protection Bureau’s new rules for payday loans and car title loans have drawn the predictable cries of outrage from lenders, particularly small storefront operators who say the restrictions will put them out of business. And it’s an understandable complaint — after spending five years researching the market for high-cost credit, the bureau has fired a shot right at the heart of these lenders’ business model. But the outrage here isn’t what the regulators are doing. It’s the way these lenders have profited from the financial troubles of their customers. As the bureau’s research shows, payday lenders rely...