I’m not convinced that all the self-published authors who are doing well are putting out the best possible product. I can think of one or two whose (admirable) skills lie more in managing their bids for Facebook ads than in actual writing. But let’s assume I’m wrong about that. I’m less interested to know what all the successful authors are doing than in finding out how many of the authors who do all those things are successful. And, if I have to subsidize my writing by other activities, I’d rather do it by working in IT than by learning to be a marketer, something for which I’m quite sure I have no aptitude.
I believe that anybody who has a very large mailing list with a high conversion rate probably built up the bulk of that list years ago. It seems unlikely that anybody who has started to build her list in the past, say, four years can expect to do nearly as well. I can’t prove that, of course, but it looks as if nobody can prove anything about the current state of publishing. As for advertising, well, as I implied above, that’s a specialist skill that only a small minority of authors will have the patience, ability and capital to develop.
I hope for the sake of people in other lines of business that (self-)publishing is not a business like any other. If it is, then small businesses in general have a dismal overall rate of return that is also extremely unevenly distributed. And the majority who fail in the first year don’t just quietly go out of business but continue to pursue their “dream” long after it makes sense to do so.