I'm not trying to sound like a hardass, but I used to have some rather bad habits. So in my case, and I'm 26, I see watching sci-fi, talking on the internet, playing video games, ect as far healthier enterprises than what I have done and could still be doing. I know that the original question is, by being such avid sci-fi lovers/geeks, are we in fact wasting time that could be used for building inter-personal relationships and enjoying the 'outside' world? For me at least, a little bit of that stuff goes a long way. So if people think I "need to get a life" that's fine, but I'm pretty happy and pretty proud of myself.