I guess it is still undecided if such an ego is beneficial or harmful. We all know people who made a good career with that attitude.
I think at least one should be able to believe that one is right and the rest of the industry is wrong. Sometimes it really is true. As an example, most people on news.YC seem to believe that Java is bad, in contrast to almost the entire industry. (I am not sure what is true in that case).
I could at least point it out to the Google case. They were right, and all the industry was wrong to believe that there was not a market in search.
On a related note, one should ennounce a law similar to Godwin's law, but talking about Google instead.