Many people want to be “different” from others, especially during their teenager years. They want to look insane in the eyes of others. “You are crazy!” — can be considered a compliment rather than a resentment. However, such behavior is completely normal to me, and I wouldn't consider such people crazy. They all look the same from the outside.
It all comes down to being authentic. If you are not true to yourself, you are just pretending to be someone else just to differentiate yourself from others. From your internal point of view, you cannot be different from others if you just be yourself. When you are trying to “be yourself”, when you are consciously thinking about it — contrary to what you think, you are actually being someone completely different — some imaginary personality that is usually inspired by well-accomplished authentic personality that you believe to be true yourself. You are not that person yet, but you are trying to become them.
That's why in my experience, not comparing yourself to others and not trying to “be different” — contrariwise makes you actually different. While everyone is trying to be someone else and pretending to be insane, you are just staying completely sane and true to yourself internally. And that, surprisingly enough, usually makes you look insane to the world! It makes you vividly different from others, it makes you authentic.
— Inspired by mine and @lucjah words.