I've had the same qualms, my guess was always that it is subsidized by those that use the rewards cards in a suboptimal way, such as carrying a balance and payi

I've had the same qualms, my guess was always that it is subsidized by those that use the rewards cards in a suboptimal way, such as carrying a balance and paying interest. Either way, the end result has been me having a desire to be on the rewards card side and using it for a net gain.