Selling a book is no way to make a living. Writing a book will probably cost more than it ever earns, between lost potential wages and the emotional toll of the publishing process. Novelist Kim Triedman explains at Beyond the Margins:

I started writing my novel around 15 years ago. I was raising three kids, working part-time, and – at the outset at least – writing mostly in the middle of the night. It was not a schedule I could maintain for the long-term, and after some months I decided to leave my part-time gig and devote myself fully to the novel.