I do volunteer, I'm active in tutoring underprivileged kids for their SAT/ACT's, and otherwise help immigrants fill out their N-100 forms. I take Arabic classes in my spare time, and I fill my free time with various other hobbies (rock climbing, hiking, etc). And that's great that I have an impact on a local community, but in the end, why does it matter? Any bozo with two brain cells to rub together can have an impact on their local community. Aren't all these hobbies just escapism from the fact that my life is centered around this 40 hours a week that I spend debugging gevent or rewriting yet another RPC service?
To me, the acceptance of the reality of "it's extremely unlikely that I'll anything that has a meaningful impact on a large group of people" is the saddest thing of all.