I have similar issues. For most of my adult life I've had so many interests that it is just impossible to keep up with all of them to the level I want. Even within computing as a field I am overloaded. I read a lot of stuff on HN and elsewhere I find interesting and I agree that it makes me feel like I should understand it all. First time I've came to that realization.
My current solution to the problem of overwhelming interests is starting grad school in CS; by going through a program, I am forced to focus on certain things by outside forces, thus saving my sanity.
I already am one, kind of.. I work for these guys: www.mitre.org
My day job is broad enough that I get to sate most of my professional desires in one way or another. Now I have grad school to explore some topics in depth and expand my education. It's working out very well so far.
My current solution to the problem of overwhelming interests is starting grad school in CS; by going through a program, I am forced to focus on certain things by outside forces, thus saving my sanity.