Giving a present might make you feel good. But as an economic transaction, economists consider it inefficient. “So when I give up $50 worth of utility to buy a present for you, the chances are high that you’ll value it at less than $50. If so, there’s been a mutual loss of utility. The transaction has been inefficient and “welfare reducing”, thus making it irrational. As an economist would put it, “unless a gift that costs the giver p dollars exactly matches the way in which the recipient would have spent the p dollars, the gift is suboptimal”.”