Those people (bosses, executives, others) that think they know it all - it's the opposite affect and it comes to be more costly too. It not only shuts off new information that can help solve problems, make more money, create new opportunities, etc.; but it is also does bigtime damage to relationships too. Look at those people that are in your life that just always seem to dismiss people because they "think" they know everything. I think we all know people like this and it is amazing how, for the most part we look to not really do too much for them or with them. There always seems to be that tension around them and that always will make things more difficult to get things done.
So again - this book (and the others I'm reading .... see my booklist on my home page), really has reminded me of things that I can do to help myself out. I hope these things help you too. Remember, you gain a very large advantage remembering that you you don't know everything. Remain humble in what you know and always look to keep that life-long learner type of attitude. Since there are so many others doing they opposite, they will actually help you more than will ever know.