Many more make a few dollars.
Some who buy a high-priced package of services for self-publsihing may end up losing money.
Some get a glowing review from the New York Times' Michiko Kakutani. (Who, as Annie Lamott once said: "The one little problem with Michiko, though, is that if she doesn't like your book, she will kill you -- cut your head off with a surgical knife, and play hacky-sack with it until she grows bored. Then, maybe in the last paragraph, she'll pour acid on it.") (Read more about her here.)
Most never get noticed.
And no one really knows why something like 50 Shades of Grey is a huge success.
When I got my first contract in 1997, the only people who self-pubbed were deluded fools who ended up with boxes of books in their basement. I still meet people who have paid thousands to have their picture book published with cheap materials and bad drawings. (Often, sadly enough, they seemed to be suckered in by a company that claims to be Christian.)
I've seen people break with traditional publishers, and people who have had success self-publshing happily sign with one of the Big Six (or is it Big 5 now?).
Recently, I've read two interesting articles about self-publishing.
One lengthy one in Time magaizne says, "Its an article of faith in the indie movement that writing fiction can be a way to get rich."
Here's a link to a pdf of the article called The 99-Cent Bestseller. he author they profile earned $352.70 in nine months. Not get-rich-quick stuff.
NPR also covered self-publishing, including looking at the prices people pay for help in getting their book in e-print.
I have put all my backlist out as ebooks. I seldom earn more than $300 a month. But hey, it's free money (I did the formatting and my husband did the covers), and it means that people are still reading my older books.
Here are links to the ooks 've put back in print and another ebook that for some reason isn't showing up when I click Kindle.