A few questions:
1) Should interests be limited in the name of doing something meaningful?
2) If interests should be limited, how do you determine what is worth spending time on so that you do not regret it after investing a significant amount of time?
3) Put another way, how do you avoid wasting your life consuming mind candy?
I spend a lot of time on the web, and in retrospect, I consider a lot of that time to have been wasted. I latch onto topics for brief periods (a few days or weeks), make big plans, then move on to a different interesting topic. I will spend large amounts of time on pretty meaningless tasks. I will spend a week messing with a music mashup that I know will make my brother laugh. He laughs. Now what? I feel like I wasted a week.
I over-analyze everything. I think part of what I enjoy is just analyzing things. I like to analyze chess games. I might spend a week or more analyzing one interesting game. Then what? I feel like I've wasted a week, even though the process was intellectually stimulating. There are hundreds of other topics that I will do this with. I will hear a comedian interviewed, and realize there is some science to comedy and what makes someone laugh, so I spend a week semi-obsessing over how to deconstruct and analyze comedy routines. Or I realize that I can compile a database of chord progressions for millions of songs and make a mashup generator. After a week or two, something else interesting comes along.
Is the answer to discover your meta-hobby, deconstructing and analyzing things in my case, and then apply that in some area that benefits others?