Real friends build you up when you're insecure and, just as importantly, tear you down when you're arrogant. Real friends call each other out on each other's bullshit. Know why some celebrities become self-centered douchebags out of touch with reality? Well, imagine having 

an entourage full of fake friends that never disagree with you for fear they'll lose you. 

The truth is real friends are willing to risk a friendship to give you a slap of reality.

(found here)