In the abstract:
> sophisticated individuals profit from reward credit cards at the expense of na¨ıve consumers.
Then in the study:
> Next, we study whether the redistribution across FICO scores is driven by differences in cardholders’ income, suggesting a transfer from poor to rich consumers. Indeed, We adopt the following terminology: “Reward cards” are credit cards that earn either cash back, miles, or points; “classic cards” are credit cards that are do not earn any form of rewards. credit card rewards are often framed as a “reverse Robin Hood” mechanism in which the poor subsidize the rich. Our results, however, show that this explanation is at best incomplete. [...] Thus, high-income consumers with high FICO scores benefit from reward credit cards largely at the expense of high-income consumers with low FICO scores.