When I was a raver, I knew DJs with egos. As a programmer, I know programmers with egos. As an actor, I've met actors with egos.
I worked for a movie star for a while. Didn't see a lot of ego. The two most successful DJs I knew were two of the least ego-driven. I think this holds for programmers as well.
I suspect ego inhibits success. I can certainly think of a few counter-examples, but it's possible each of these people would be even more successful with their egos out of the way.
All of this is a bit awkward for me as I'm a guy with a big ego. I'm sure these problems only plague lesser people, however, so I'm only blogging this for your instruction. Please curb your egos, and keep them in check, lest they ruffle my greatness.