People often assume that hoarding knowledge will protect their reputation as a "source of knowledge", and that if they share what they know, they may no longer be needed. This is not always the case.
"A year or so ago, I was working with another expert. He was more qualified than me, but he took a very different approach to knowledge. He hoarded his knowledge; he protected it, and would not share it. In contrast, I was happy to share what I knew, and I quickly built a network of people to share with.
"I was amazed to find that after quite a short time, my reputation was much higher than his! Although he was more qualified, people were now coming to me as "the expert". It seems his knowledge hoarding actually reduced his reputation, whereas my knowledge sharing increased mine!"