I think of all the writers, that Solomon had the most to say about being conceited, whether he was talking from lessons he learned like in Ecclesiastes about all being vanity. He made lot's of statements about be wise in your own conceits which is astounding given he was given wisdom as a gift from God, but seems as it was earthly cause he even caused the dividing of the tribes and his alliances by marriage's was his his downfall into pagan idolatry, Built pagan shrines, raised taxes, it seems it was cause everything was about him and not denying himself any pleasures.