Marketing is the issue. Selling yourself.
   If you want office work as a writer, technical writing is always
   available. Grant writing is always available. There's a number
   of jobs where writing in a formula style makes money and all you
   have to do is sell yourself once, to the person hiring you.

   Otherwise, you have to sell yourself to the public. I'm not sure
   how it works with an agent; I assume they help... but even
   then... look at what authors tend to have to do; make TED
   talks... conferences, book signings, etc.

   Or if you stay strictly online, web marketing of whatever means
   you can.

   Marketing. Blech. But there ya go.