You don't have to be mad to work here, but it helps. Writing strikes me like that, you don't have to be mad to do it, but it helps the process along. At the risk of labouring the point I've just sent two novels through the net to Smashwords, two pieces of work that took months of creation and then proofing, editing and formatting. Now they are out there working their way through the process to be distributed and there are no guarantees. This is a risky business. The investment on the part of the writer is huge, and the returns if you have the story everyone wants to read can be equally huge, but... and there's the rub, the answer lies out there.
Like I said, you don't have to be mad, but it is so much fun when the words are pouring out.