I am a huge fan of cross pollinating knowledge. Learning is quite simply acquiring knowledge you don't know. You won't get something you don't know by continuing to study what you do know.** More importantly I believe that a field as a whole can benefit, can learn, as we in that field seek out new bits of understanding and bring them back.
With that in mind I would like to present to you this tid-bit on leadership. Leadership may seem odd as a topic for writers who are traditionally misanthropic and solitary but if you take a moment to think about it what makes an author "great" (in the people actually hear about and read them sense) is that people follow them. People read their work and not any random authors because it is THEIR work and not just some random authors. So sit back and enjoy one of the more popular of the widely popular TED Talks.
~Simon Sinek: How great leaders inspire action from TED 2010
So... Why do you write?
Not knowing yet is alright, I am sure many great authors would just say 'because'. To be perfectly honest I'm not really sure why I write either, but I think I'll try and figure it out now. Till then, I leave you with the only famous author's quotes I could find on the subject.
"So really why I continued writing [is because] I felt there was nothing out there. So I had to continue, because they were so bad, not because I was so good. And I'm still not so good. But they're still very bad. There is still room for someone to step in here, you see?" ~Bukowski, Poetry in Motion
** Totally facetious argument based on poor definition of what "know" means, expect me to argue the exact opposite at a later date. "Almost every wise saying has an opposite one, no less wise, to balance it." ~Santayana, Essays