<prompt> Human: Some credit cards give back 5-6 of purchases in certain categories e.g. groceriesgas as cash or statement credit. How do those banks make money, especially without annual fees? Merchant discount rate is only about 3 and this doesnt add up.  <response>: They make money on all the folks paying interest and the cash back is an enticement to get more folk using and potentially paying interest.Just dont be someone paying CC interest. 