I see it as something of a spectrum. For me, it is a way of life, but there are some people for whom it is so much *more* than just a way of life. Those are the ones that I find kinda creepy. But those are also the ones who call their friends at horrifying hours and roleplay yaoi (slash anime) seduction scenes to each other for *hours* at a time and don't let their roommates get a wink of sleep. *grumble*

I guess it just depends how much of your time you're willing to put into it and how worried you are of your fandom time becoming part of your serious time.