I used to be in a similar situation (smartest, most innovative person in a team of nearly 2000 developers), then I jumped ship to a smaller but way more competent team. One one hand, now I occasionally get schooled by some of the smartest people around and love it, on the other, I (very rarely) miss being the king of the hill. I have since come to the conclusion that happiness is not (and should not be) tied to your work identity, what matters is people, friends, family and how one contributes to increasing the beauty of the universe. Sounds lofty and a little vague but that is by design, you have to find what motivates and excites you.