Based on a 2013 survey, where authors responded to a variety of questions, Weinburg analyzed some really important and interesting facets related to the self vs traditional publishing debate. Three types of authors were identified, ‘Self Published’, ‘Traditionally Published’, and ‘Hybrid’ (which means a combination of both other types).
In looking at the graphs, the bottom line to me, is that self publishing is a risky game that, while personally rewarding, won’t bring in any real profit on its own. However, at the same time the most driven and focused authors, as inferred by profit and number of manuscripts produced, do not limit themselves from any outlet, but make up the majority of the ‘Hybrid’ category.
Maybe these ‘Hybrid authors’ start out self publishing, and then move up to traditional publishing. Maybe traditionally published authors break away and make a go of it on their own once their name is established. I imagine that it isn’t as simple as that. Only one thing is really clear, the authors who earn more are those who produce more manuscripts, are more focused on their goals, and don’t limit themselves to any one publishing format.