[pavelludiq]

True about the kernel, but I've recompiled many of my tools(for example linux repos sometimes provide outdated versions of packages and I need something newer). I often dig in source if I find bugs, or under-documented areas, sometimes I just want to know what is really happening. True, that doesn't make people who don't do that any less "pro", but it does make me sharper as a practitioner. I earn a deeper knowledge about my tools and my environment and occasionally pick up good ideas, or learn some horrible truth about a beloved tool. Programming is fairly unique in the sense that our tools and our products are made of essentially the same stuff. At the very least I consider this a form of exercise worth practicing on a regular basis. It's not strictly work, and not strictly a hobby.