Btw, just to clarify, in case my tone comes across as negative it's because there was an awful lot of baseless hype about self-publishing a few years back (namely around 2012-2015 I think). There was the promotion of misleading self-publishing statistics, and a whole load of untrue "facts" bandied around - one being the lifetime worth of a self-published novel was around $500,000. I read of people turning down Big 5 trad publishing contracts because of this. SP authors who had exceptional sales were promoted as the norm - after all, if they could do it, so could anyone else.
In a way, there
was a zeitgeist and some early adopters did very well, partly through limited competition (people were often still wary of SP), and others discovered really big niches trad pub wasn't touching - military SF is a good example.
But once you looked more closely at the overall statistics, while it was true that SP books were selling huge volumes, most of this was millions of people SP'ing and selling a few books to friends and family. For example, if trad publishers put out 500 new fiction books in a year, and sell an average of 20k copies each, that's 10 million in sales - but if 1 million SP authors sell 10 books to friends and family, that's also 10 million in sales, with the caveat that many of these SP "sales" are free downloads anyway. That's how you have to look at SP stats.
Also, I think even a few years ago it was suggested that most SP books average 12 sales
over their lifetime. With the market being even more flooded now I suspect that figure is much lower.
We have seen people at chrons be very successful with SP, though:
Ralph Kern built on strong early success with
Endeavour, and
Nathan Hystad became a general best selling author. But they are the exceptions, not the norm.