Rational? I’m at a hotel and was given a coupon allowing me to eat the excellent breakfast buffet at no cost. Sounds good; but instead, I go next door to Caribou Coffee and buy a coffee and blackberry scone for $5. Is this utility-maximizing?
I think so. I know that if I get the “free” buffet, I’ll eat a lot—probably orange juice and a large Belgian waffle with lots of syrup. Having pigged out over Thanksgiving, my weight is already up. Spending the $5 is a self-control mechanism: I know that once I’m done at Caribou, I’ll be sufficiently less hungry that I won’t want to spend time at the buffet (and won’t have eaten more than I should). There’s more to utility than increasing income and/or reducing spending!