We don't always do what we think is best. Other things matter. Behavioural Economists have devised various games to try understand how real people deviate from purely rational behaviour. One of those experiments is called the 'Ultimatum Game'. Two people play. One (The Proposer) is given some money, say $100, and told to offer some of it to the other player (The Responder). The Responder can either accept or reject the offer. Rejection means neither player gets anything. In a purely rational world, if the Proposer offered $1, the Responder would be better off accepting the arrangement. In experiments, offers of less than 30% are often rejected.
Concepts of fairness, justice, altruism, vengeance, and our spice rack of emotions get involved in most decisions that we make. Most of these more fuzzy, juicy concepts don't have the benefit of quantitative answers. There is no way of counting them. Of comparing them. Of ranking them. I think this is part of intelligence. It is why people are still (for now) so much smarter than computers. Computers think in Ones and Zeroes. Black and White. Right and Wrong. This is limiting. The fun stuff, the painful stuff, the stuff with meaning... happens between the facts. It happens in the gaps. In the spaces. In the relationships.
Understanding is a dance of that which we can count and that which we can't. The beauty of the dance lies in the stories fact and fiction create together.