I've heard that question a few times in my life. (Including from ex-wives.) To me, the simple fact that you would have to ask means that you won't be happy (or perhaps even understand) my answer. I am going to share my own personal reasons here. Some of them will seem silly, a few will definitely sound selfish. Still, they are mine and I am not ashamed of them.
First off, if you know me personally, it comes as no surprise that I am a bit of an attention whore. Simply put, I like being in the spotlight. I've been the lead singer and a guitarist for a few bands. Nothing major...but an absolute blast. I've played in front of a few hundred people. Even on the tiniest stage, I always treated it like it was a packed arena full of thousands. I put my heart into it every time I stepped up to the mic. When I strapped on my guitar, I felt like Ace Frehley or Stevie Ray Vaughn...even though I played like...well...me.
I have a hefty amount of stage credits to my name; having been in shows like Pippin, Oliver, Joseph and the Amazing Technicolor Dreamcoat, and The World According to Snoopy. I discovered my knack for the stage in high school and decided to pursue it into adulthood. I feel fortunate. I never auditioned for a show that I wasn't cast in during those years. I have a ton of great memories from that era in my life.
Still, I always had that yearning to write. It has been part of me since I was a kid telling bedtime stories to my teddy bear. I have just loved the idea of sharing a story. I was the kid on the camp outs who had a million ghost stories. When I got to high school, I took every writing class I could get in to. When the teacher in my Creative Writing class would ask if anybody wanted to share their work, I always raised my hand. The payoff would come after class when the other kids would give their feedback. My favorite comment came from the pretty girl who didn't ever remember my name. "You should write for a living." I'd like to say that she finally remembered my name but...no. I was still invisible to her. Still, she did smile and occasionally say hello in passing. (Wasn't high school great?!) The biggest thing that I kept hearing was that I had a knack for creating something on paper.
The problem I faced when I was young is nothing that hasn't plagued most teenagers: focus. I was in the Navy...seeing the world. I enlisted as a submarine sonar technician right out of high school. It was the 80s. The US and the (still in existence) USSR did not get along. My job was to find and classify Soviet contacts of interest. Very Hunt for Red October. I would write in fits and starts for several years.
In 1989, when I left the US Navy, I would seriously consider what I wanted to do with my life. It always came back to writing. Whether I was writing comedy bits for the morning show at the radio station, or ad copy (the least glamorous writing job EVER!)...writing was my love. Next time I will dish up dirt on a relationship that almost put me out of action forever...and the one that restarted me on this path.