I have personal anecdotal evidence. One friend will make increasingly frivolous purchases as they approach rewards thresholds. They ended up with 5-figure cre

I have personal anecdotal evidence. One friend will make increasingly frivolous purchases as they approach rewards thresholds. They ended up with 5-figure credit card debt and a net loss of funds because they considered rewards at time of purchase, but not the interest on the credit for not paying full statement balance. I'd be curious to see a more formal academic analysis of this, however.