Back in the old days (2008 and before) authors were at the mercy of two types of publishers.
First were the traditional print houses who misunderstood the impact of the 2007 release of the Kindle and went on with business as usual. Their sales began to slip, their revenues dipped, and they circled the wagons. And by that I mean, they started buying only what they already knew would sell. Literally, "Give us something different, as long as it fits these boxes."
OUTCOME: You don't fit in the box, we won't buy your book.
Second were the vanity presses; self-publishing at it's absolute worst. Vanity presses print anything they are given, regardless of quality, because they make their money from the authors who pay them thousands of dollars to print X-number of books, which the author is then responsible to sell.
OUTCOME: Awful books, bought and sold at exorbitant prices, and authors losing quite a bit of money, not making it.
Then Amazon bought a company called CreateSpace, and expanded its offerings to print-on-demand books. In 2009, Amazon signed a distribution agreement with Ingram, and now those books can be ordered by bookstores.
OUTCOME: Without any upfront investment, authors can get their books into print at a decent per-copy price, and sell them internationally through Amazon.com. (Ditto for eBooks on Kindle, Nook, etc.)
Just because we can, doesn't mean authors should run out and upload their latest gem. As shortsighted as many of the traditional publishers have been in this shifting business, they provide some EXTREMELY important services:
1. They tell authors if their writing skills are good enough.
OUTCOME: Too many self-publishing authors fail to get honest feedback before they publish. Their writing makes me wince. These authors will not have repeat customers.
2. They edit the manuscripts. They looked for mistakes in spelling, grammar, pacing, continuity, characterization, plot, punctuation, etc.
OUTCOME: I have seen self-pubbed books which were such a hot mess that I wondered if anyone looked at them at all. These authors will not have repeat customers, either.
3. They promote the authors.
OUTCOME: If no one knows you exist, they can't buy your books! Self-publishing authors have a long, hard, expensive, time-consuming, and discouraging road ahead of them.
So, what's my point?
You can do this.
Don't publish prematurely.
Know what you are getting into.
Take yourself seriously as a writer.
Be willing to take the hard criticism.
Get professional opinions about your manuscripts.
Be dedicated to learning to write better and doing your best.
Don't spend more cash on promotion than you can make back in sales.
Quality, quality, quality, quality; details, details, details, details, details.
Don't make a bad publishing decision. Because digging out from under the fallout will take exponentially more time, effort, and expense than if you step back, regroup, and do it well to begin with.