Nate over at The Digital Reader linked to an older (June) BookBub piece:
Weirdly, despite the atrocious title and the not-so-good summary, the slide deck is a moderately good presentation of what I think of as the Joe Konrath Explanation of Why You Don't Need a Publisher. Basically, if you write good genre fiction, and you write multiple books, and you have one or more priced low consistently (doesn't have to be the same one -- he's entertained and experimented with a lot of pricing approaches over time), you'll attract fans and they will buy the rest of your books full price and keep doing so over time.
The BookBub piece is a survey that explains the readership that is buying those books.
It's not actually a surprise: mostly middle-aged and up women and some men, had kids which are probably grown, have median or better household income and are self, part or full time employed (but if the latter, probably not in a crazy-making, 110% of your life committed to the gig type job), reads a book or more a week and has probably, over time, gotten more than a little tired with the rate at which TradPub puts out the stuff they prefer to read. _I_ think, but BookBub didn't explore, that these readers are also kind of tired of some of the limitations TradPub puts on the books they publish (that is, a lot of the bargain hunting romance readers are also looking for erotica with a real relationship and an HEA that TradPub historically avoided; there's probably a related phenomena on the thriller and/or horror side, but I don't read over there so I wouldn't know).
But it is a decent survey and they drew a reasonable conclusion from it. I will also point out, however, that Amazon has been working on converting this crowd to a subscription model with Kindle Unlimited; it remains to be seen how this will work out for authors writing to this group. I think David Gaughran has been trying to figure that out.
BookBub would appear to have a major horse in this race.