Narcissists live and die by their own version of the truth. Is it the truth if reality has been distorted? A narcissist believes it is. Extreme cognitive distortions and rigid unconscious defense mechanisms change a person’s perception of an experience. Paramount distortions and defenses are typically employed by a person with a narcissistic personality disorder; both alter reality in order to make it more palpable for a fragile ego.
https://www.psychologytoday.com/us/blog/peaceful-parenting/201906/does-narcissist-believe-his-or-her-own-lies