Egocentrism:

Egocentrism is cognitive difficulty in understanding others’ perspectives, as  differentiated from (or as important as) one’s own thoughts, interests, and opinions—often leading to an assumption that others think, feel, and see things the same way as oneself. Stemming from developmental psychology, egocentrism is the inability to accurately perceive or understand others’ perspectives. In contrast, a narcissist is more concerned with the perfection of their mental or physical qualities, trying to be the center of attention. Theories by age group:

• Young children: World renowned Swiss psychologist Jean Piaget theorized children in early stages of cognitive development are naturally egocentric. A young child believes, if they hide from their parents, they’re invisible to them.
• Adolescent egocentrism: David Elkind, expanding on Piaget, introduced the concept of teenagers struggling to separate their thoughts and feelings from those of others, believing everyone is focused on them and judging them harshly. He identified two forms: imaginary audience (belief others are constantly watching/judging) and personal fable (belief one’s experiences are unique/special).
• Adulthood: While less pronounced, egocentric tendencies can persist and potentially lead to misunderstandings and conflicts in interpersonal relationships. Egocentric adults may assume their own experiences and perspectives are universally shared.