Dave Winer says why he loves what he calls professional users:
We should be teaching young people how to be great users. How to contribute to the projects that make them more effective at doing what they do. The best form of contribution is to communicate clearly about ways the software isn't working.
There's a common, incorrect, belief that users don't matter, they can't do anything to help open source projects. Nothing could be further from the truth. Just having one user put a bit of serious concentrated time in working on my product made a huge difference for me as a developer.
h/t to club member Jeremy Felt for this article!