Rolf Degen summarizing... Around the age of 5 or 6, it dawns on children that others sometimes consider themselves better than they are, and it displeases them

The better to fool you with: Deception and self-deception. Jade Butterworth, Robert Trivers, William von Hippel. Current Opinion in Psychology, June 9 2022, 101385. https://doi.org/10.1016/j.copsyc.2022.101385

Abstract: Deception is used by plants, animals, and humans to increase their fitness by persuading others of false beliefs that benefit the self, thereby creating evolutionary pressure to detect deception and avoid providing such unearned benefits to others. Self-deception can disrupt detection efforts by eliminating cognitive load and idiosyncratic deceptive cues, raising the possibility that persuading others of a false belief might be more achievable after first persuading oneself. If people self-deceive in service of their persuasive goals, self-deception should emerge whenever persuasion is paramount and hence should be evident in information sharing, generalized beliefs about the self, and intergroup relations. The mechanism, costs, and benefits of self-deceptive biases are explored from this evolutionary perspective.