You talk as though there were a choice! I've found that it's just something I do, irrespective of whether an audience will ever see the stuff or like the stuff...
I have always written (poems, songs, cartoons, sketches) for as long as I can remember. I have always got a buzz out of the creative process itself and don't particularly crave an audience, although it is obviously desirable. Fame, money, etc. Sure...
But if the boys turned up in the De Lorean and told me I wasn't gonna make it then to be honest that would just confirm what I've always suspected anyway, so I think I'd just carry on. First things first, I write for myself, not for any other bugger! If others like it, fine... if not, well, that's fine too!
But if a Producer or Editor said, "change the stuff and I'll use it AND I'll pay you..." then I would change it, why not? I'd still have the original anyway. And I sure could use the money...
But the driving force as to why I write comes from something in the creative process itself, I dunno what though...
No set career plan, just keep going and see what happens... nothing much has so far... to a great extent in the entertainment business I think you do have to MAKE it happen, so to be driven by the desire for success is probably important, but I've never really been driven that hard by that... I wish I had...