There are lots of reasons why self-publishing success stories tend to concentrate around writers of “genre” fiction, but it’s a mistake to assume that success is impossible if you write literary fiction or historical fiction (which tends to get lumped in with literary fiction, even though it’s just another genre… like literary fiction!).
The first is demographics: romance and erotica readers were the first to switch to digital, followed by mystery and thriller fans, leading to the success stories of Amanda Hocking, Joe Konrath, and John Locke.
I remember SF/F authors complaining (back in 2011) that their readers hadn’t switched to e-books yet, casting jealous eyes at the outsized romance audience. But as readers did move across, we saw people like David Dalglish and BV Larson breaking out, and the rest of “genre” fiction soon followed.
The rise of “genre” self-publishing was also aided by the mistreatment of the midlist by large publishers: falling advances, worsening terms, and the shifting of the marketing burden onto the author’s shoulders. With bigger names jumping ship and striking out on their own, the increasing selection of quality self-published books at very low prices (and often exclusively available as e-books) acted as a strong pull factor for readers of genre fiction to switch to digital.
Non-fiction has been slower to go digital for a few reasons. First, technical limitations of e-book formats and the devices themselves have made the digitization of anything other than straight narrative text troublesome – even the minor technical challenge posed by something like footnotes has yet to be resolved in a satisfactory way.
On top of that, non-fiction authors tend to be treated a little better by publishers, especially in terms of advances – so there’s less of a push factor encouraging authors to self-publish. This means less big name authors dragging print readers to digital with low prices and digital exclusivity, and, thus, a smaller reader pool for non-fiction self-publishers.
The case of historical fiction and literary fiction is a little different. Weak digital sales from large publishers, and the relative lack of self-publishing success in these genres, has led some to worry about the future. But I think something else is going on here.