[stevelaz]

It's when you start to think you know everything that people don't like to work with you. I haven't met that many people in my software career ~15yrs that have enjoyed working with a know-it-all.

You can of course be super smart at your job and know a TON, but when you start acting cocky and like you know everything it usually doesn't end well.

[jqm]

I can tolerate know-it-alls when they really do know a lot more about something than I do and are willing to share.

However in my experience, the majority of people with a know-it-all attitude are simply blowing hot air and trying to cover for the fact that they really aren't nearly as smart or knowledgeable as they would like to be.

Most truly smart and knowledgeable people I've met have been amazingly humble and usually fairly quiet about things. The qualities of quietness and humility lead to learning.