He links it to self-deception. In fields where we have ancestral traditions, such as pillaging, we are very good at predicting outcomes by gauging the balance of power. Humans and chimps can immediately sense which side has the upper hand, and make a cost-benefit analysis about whether to attack and take the goods and the mates. Once you start raiding, you put yourself into a delusional mind-set that makes you ignore additional information—it is best to avoid wavering during battle. On the other hand, unlike raids, large-scale wars are not something present in human heritage—we are new to them—so we tend to misestimate their duration and overestimate our relative power.
Taleb, Nassim. The Black Swan (p. 147). Penguin Books Ltd. Kindle Edition.
Looool. This is one of the reasons for our tendency to not change a decision after we have reached it—confirmation bias (is it that bias btw.). Very nice! So, we made decisions in predictable environments (outputs tied to inputs, repeatable past, tangible, etc.) where being an expert truly yielded bigger results. So intuitions were often right and changing one's mind after the decision wasn't because it hindered the execution.