Presumably they do make money on the annual fee, even if you spend absolutely nothing on it. My total spend for all of 2018 was around $300 (mostly on Amex offers). I've actually already surpassed that this year, as I just spent $1500 on airfare on the card. I'll probably spend a couple thousand more on airfares this year as I've started to shift some spend over to Amex and MR (which is useful for transferring to Hilton whenever they have transfer bonuses) because I have an excess of UR points at Chase (around 500k) that I haven't been able to use. I still have around 250k UA RDM and I'd have to exhaust those first before I start dipping into my UR points, so it's probably going to be a while. In any case, Amex *does* have to be making some money even if you spend nothing on the card and only pay the AF.