I'd love to be able to find something good to say about the act of self-publishing. Perhaps there is just one thing that's not discouraging, and it's that the numbers of vanity publishers who prey on writers with big egos and little understanding of the publishing business, have reduced in the wake of the rash of self-publishing that goes on now. The only thing that anyone else has ever offered up as 'a good thing' is the idea that there is always the chance for a self-published book to be 'discovered.' But I would say why publish it yourself in the first place if really you wanted it taken up by a professional? That's a difficult question to answer with any honesty, unless self-publishers are prepared to admit that they have gone down that dreary route in desperation because they can't tolerate being rejected by the industry and have actually tried to get their work accepted by a publisher. Then you'd have to ask how many rejections does it take to throw someone into self-publishing mode? What? ten, thirty, seventy rejections for the same piece of work? What?
The truth about idea of the self-published book that gets picked up by a real publisher is that it's simply a stupid myth that further encourages would-be authors into that act of sheer vanity. It might have happened once or twice, but that's all, and it did NOT happen to 50 Shades, by the way.
The other observation that's worth mentioning is that every time you go on a tour of publishers' sites, you see that the numbers of them that are refusing to consider any 'self-published' works is increasing ... exponentially. I suppose it must be like someone walking into a shoe menders with a home made shoe and asking if it could be fixed.
I find self-publishing utterly bewildering, because surely there is zero credit in doing it? Surely you just come out of it looking like a vain egocentric person... who quite likely isn't really a writer. And isn't that shaming? Perhaps the people who resort to it, underestimate the level of patience, discipline, love of the craft, self-belief yet lack of ego, that it takes to become a published writer. Quite recently someone in the publishing industry likened 'self-publishers' to people singing opera in the bath, or words to that effect, in other words not the real thing. I have my own hardly ever spoken aloud word linked to the idea of 'self'that I think is an appropriate description of the 'act.'