1. As I said before, it's good for my soul. I tend to get very cranky if I haven't written for a while. (This could also mean I'm addicted.)
2. It's fun. I love putting characters through tons of crap and watching them fight their way out.
3. It's simple. You only need imagination, pen and paper. I wrote almost all my second book in one five-dollar notebook and a couple yellow legal pads.
4. It's also pretty cheap, unless you get the conference bug.
5. I'm no good at high finance.
6. I get to be anti-social and other people think it's cool.
7. I have to.
If you don't understand that last one, there's no way I can explain it properly.
I can't not write. That's all there is to it.