Originally Posted by
Beckles
I'm not sure we have any way to know that the credit card companies bear the full cost of sign-up bonuses on their own. In general, it is not uncommon for bonuses to be jointly funded by the airline and the partner, I don't see any reason to believe that does not occur with credit card bonuses too.
I never thought of that. It makes sense for the airline to subsidize the bonus, because receiving that chunk of miles gives the customer a good reason to choose that airline for any paid travel.