Of course, to a level of self-defense, there are some who engage in said activities (even heavily, if not life dedicated) who are quite normal folk.
I have been a fanatical fan of Star Wars since my brother took me to Ep 4 in 76 (for the record, never been to a convention, nor dressed up for any movie premier), I played, and still play role playing games on occasion, and I'm active in at least one MMORPG at the moment.
On the other hand, I'm a sports fan, play raquetball, love camping, skiing, hiking, all the things geeks are usually afraid of. Granted, that's not to say I'm normal or anything....