Decoding the Puzzle that is Me

I am simple, yet I am complicated beyond comprehension.
I understand myself too well, to know that I will never fully understand myself.
I fill myself with thoughts of happiness, yet I think too much to be happy.
People claim to know so much, yet they will never know enough to be me.
I am so different from everyone else, but I know enough about the world, to understand that I have to appear just the same as everyone else.
I think so much alone, but people are the real source of my energy.
I hate to be alone, can you solve the puzzle that is me?