Whenever you hold useful knowledge that many other don't know about; it could be completely forgotten. Either everyone who knows of it bring it with them to their grave, or nobody gives a fuck about it. What does it matter to you? Well, without other people, developing the knowledge, and seeing how it can be used more and more won't be as easy. Sharing knowledge is good, and we've been doing it for all of these years through the human history. It's why we humans have evolved so well.

During the dark ages, people didn't share as much, and we were left in darkness, but then people started sharing their ideas, and knowledge; and all of a sudden there was development, and standards as well as efficiency.