Your involvement as an author doesn't stop once they send you a check and the book hits the printers. There's still marketing which as a new author is almost entirely left on your shoulders if you want your book to be a success. I'll get into that later in another blog post.
The How Stuff Works site I linked earlier follows the story of one man who self-published and ended up doing quite well for himself, very inspirational story. Some authors choose to remain self-published, as they end up getting (usually) a bigger slice of the profits, others might use it as a marketing ploy to get a big-name publisher to pick them up. Either way, you've made a name for yourself if the book (and your marketing) is a success, and next time you might be able to just sit back on your piles of cash!
Print on Demand machine products like the Espresso Book Machine might make it incredibly easy for authors to not have to keep stocks of books at distributers or in their garage. Have one of these machines sitting at your local mall and any customer might be able to pull up your book, insert some cash, and 4 minutes later they have your book in their hands. Another option, and one I'm particularly fond of, is e-books, like the Kindle (which I own btw) or places like Smashwords. I foresee a day short-coming where students will be carrying around an e-book reader instead of 60 lbs of books, that will be an awesome day indeed!