Habits of Genuinely Likeable People#8
.. Because other people are always more important.
You already know what you know. You know your opinions. You know your perspectives and points of view.
That stuff isn't important, because it's already yours. You can't learn anything from yourself.
But you don't know what other people know, and everyone, no matter who he or she is, knows things you don't know.
That makes other people a lot more important to you than you -- because you can learn from them.