I consider myself as one as far as technical competence is concerned, though not as much by attitude. I would typically rate at 10 in most of the teams I have worked.
But having managed a few high profile developers later in my career, I would definitely say they are detrimental to the health of teams. In most teams, you just need average or above average developers who can churn out pages of code, once specifications are given. This is very much true in business computing, though it may not be valid in product development and system software.
Rockstars have their uses though. When the time is short, or during critical situations when quick thinking and a fast hack is required, they come in handy. So most teams tolerate having one of them around. So long as there is a decent manager who can keep such developers controlled and balance team dynamics, they won't cause too much trouble.