I've heard two very conflicting accounts on the issue of turning ones hobby into their job. I've heard that the hobby is passionate and leisurely, so turning it into ones job potentially sucks the passion right out of it. That the fun is wiped clean once you HAVE to do it, as opposed to doing it whenever you'd like but with no pressure to hit deadlines or book a certain amount of shoots to survive.
On the other hand, I've heard that turning ones hobby into their job was the best move some photographers ever made. They get to do something creative all day. They are not always tied to a desk and chair; they can be outside enjoying a nice day with nice people. They got to do what they love 24/7 AND got paid to do it. According to them, "How many people can say that?!"
I haven't successfully turned my hobby into my profession, so I am unsure of which side I'd take. As of right now though, I think I'd absolutely LOVE to take photos and get paid to do it. I have had this hobby for nearly 5 years now and have loved every minute of it. I have experimented with subjects, with editing/processing styles, and I have spent a fair amount of money trying to better myself through good equipment, good editing software, books etc. I think it'd be nice that what I spend most of my money on (other than bills), had a nice turnaround and was paying for itself. Eh, maybe one day it will :)