No, the credit cards are making plenty of money off of you: probably on the order of $150 a month. From there it costs $.35 to bulk mail your bill, and $.25 to process your payment (including the cost of running the web site you pay it at). There is also your share of the advertising they do, and other overhead that I don't know how to place. Still their profit off of you is over $100/month!
I'm not entirely convinced that the person who maxes out their cards and pays interest is actually more profitable - a lot of them will end up defaulting in a few years and paying less than they actually put on the cards in interest. I can't be bothered to look up the numbers (if they are even available) to see if that is true or not.
Of course I made up the numbers above. They are ballpark (and somewhat variable), but they give you a picture of the truth: your are insanely profitable to them.