“Most people strongly believe they are just, virtuous, and moral; yet regard the average person as distinctly less so.”
A comprehensive study from Royal Holloway, University of London, conducted in 2016 concluded that :
“[…] moral superiority comprised a substantial irrational component; the absolute and relative magnitude of which was greater than that observed in other domains of self-enhancement. Indeed, virtually all individuals irrationally inflated their moral qualities.”
The effect is so prevalent that the research team ask if the illusion might have evolved due to some evolutionary benefit. If there is one, it has yet to be explained how it arose and why it is so ubiquitous.
See: The Illusion of Moral Superiority Social Psychological and Personality Science, Volume: 8 issue: 6, page(s): 623-631