According to a recent article in The New York Times, self-publishing is no longer just about the vanity presses. Of course, we've known this for years, as a sort-of mashup between traditional publishing and typical POD publishers, which are largely self-publishing companies. More than half of the books published last year--somewhere between 150,000 to 200,000 out of 350,000 titles--were self-published.
Much of this success (or rather, publicity) can be attributed to the Amazon self-publishing boom with CreateSpace and Kindle Direct Publishing. The New York Times' attention can also probably be blamed on Fifty Shades of Grey, which as most people know, started out as a self-published, hastily doctored Twilight fanfiction. After mentioning two self-published books which did well ("Fifty Shades of Grey" and "The Fine Print of Self-Publishing," neither of which apparently warrant correct punctuation for book titles), the article gives the disappointing caveat that most self-published books will only ever sell between 50 and 100 copies, a dismal quantity at best.
Many authors who self-publish might not care, having published the book for various reasons. Often authors don't care about getting their book to a wide audience, but just about getting the book out at all. Of course, many (most) might just be overly-optimistic. As one self-published author whose book got bought by a big house put it, "The biggest thing you have against you in trying to sell your book is that people don't know about it."
This is true, and not limited to self-publishing. Other articles have been coming out about how difficult it is to get books noticed by the public, through online and traditional marketing methods. But publishers have contacts in the business, and that's why publishing through other methods can be beneficial. Though we publish books through print-on-demand technology, a much more cost effective method than large print runs, we market our books using both traditional and online methods. This can be a great help to authors who don't know where to start. Of course, the author is always the most effective marketer, especially of non-fiction books, since they ideally have an audience and platform already built up and can reach them most easily. Basically, as the article states, it's nothing revolutionary to get people to notice your work, but it does take a lot of effort.
The point is, The New York Times has finally gotten around to noticing that people are self-publishing. That it can be a good choice for some authors, but that many won't make it. That it's hard work. Welcome to the 21st century.