The harm, of course, is that the banks end up paying billions of dollars in flights and other rewards for customers who are not paying fees or interest on their cards, and that these costs are passed on to consumers as higher ticket prices. Some credit cards have tried to clamp down on these hacks. In 2016, Chase instituted a rule that a consumer won’t be approved for most Chase credit cards if that person has opened five or more credit card accounts across all banks in the past twenty-four months.
