noun, noun which may take the genitive case particle 'no'
self-centeredness; selfishness; egotism
Describes a person or attitude that puts one's own interests, desires, or perspective above others. Often used critically.
I'm fed up with his self-centered attitude.
With a selfish way of thinking, it's hard to get along with others.
利己的 is a more common and direct adjective for 'selfish', while 自己本位 is a noun/no-adjective that emphasizes making oneself the standard or center.
自分勝手 is a casual, everyday term for selfish behavior, whereas 自己本位 is more formal and analytical.
Compound of 自己 (self) and 本位 (standard, basis). The term likely emerged in modern Japanese to describe egocentric attitudes, possibly influenced by Western psychological concepts.