There are many findings in psychology which seem puzzling from the standpoint of utility maximization. A favorite one is that humans are often willing to punish a wrong-doer at significant cost, even though the damage is already done. And in a "1-round game", this is indeed stupid. But this instinct evolved in a social animal that historically was in contact with the same individuals of its species for most of its life; punishing a wrong-doer after the fact still makes similar wrong-doing in the future less likely, and serves as a warning for those thinking about it.
It is likely that similar puzzling findings in psychology, which are puzzling when viewed in a one-round game, are actually utility-maximizing when considered in the context of longer time spans.