Yesterday's thing with Amanda Hocking resulted in a lot of discussion about success and failure, and what constitutes each. And I have to say, one of the things that is nice about self-publishing is that you yourself get to determine what is a success and what is a failure.
Obviously, there's a dark side to this: If you're a delusional narcissist, then you can spend an absurd amount of money, get absolutely no results, and be completely pleased by it all. (I'm not kidding: I met a woman once who, when she found out I worked in publishing, told me about this guy who had paid to have a novel ghost-written. He was up front about the fact that, no, he didn't actually write it, he had paid someone else to write it, and the book sucked. Yet he was totally proud of himself.)
Let's say that you're not crazy, and instead you're a reasonably good writer who has produced a reasonably good book. But your editor jumps ship, and your work is abandoned. Or, you sold a publisher a vampire romance, and they decide that vampire romances aren't hot any more, so they're not going to print it, but they're not going to give you your rights back. Or they go bankrupt and the rights to your work are seized as an asset. Or your book just doesn't sell a huge amount in that three-month window, so your name is mud. Or, or, or, or, or, or.
My point is, it's really easy to get pegged as a failure in traditional publishing. It can happen for any reason, or for no reason at all, and the person who was championing you at the beginning of the month can be dumping you at the end of it. That's mainly because of the lottery aspect of it all--chances are you're a losing ticket, so people are primed to ditch you and move on to someone else.
What's nice about self-publishing is that you can be a success with sales that in traditional publishing would be considered a failure. You can also be a success with a time frame that is unacceptable in traditional publishing--trust me, traditionally-published authors don't get to decide to hold off on marketing until they have more books out. In self-publishing, there are do-overs--you can fix the cover and the description and even take down the book and rewrite and put it up again under a different name if you are so inclined. There's no one else deciding when to give up on your book--that's up to you.
Since you don't get punished for "failure," you can earn what you earn--you don't have to make X amount of money or your career is over. It's easier with self-publishing to get to the point where you can write books for a living, but if you don't, so what? I was talking to one writer who doesn't make nearly enough to earn a living, but who puts all the money earned from self-publishing into a vacation fund--voila, instant motivation! And instant success!