Okay, a qualification to the post's title: whether or not you should self-publish your book depends on your goals. The common example of wanting only a couple dozen copies of a family history is a good enough reason to self-publish, if you are willing to invest the money. And the costs can be substantial, as laid out in the following article from this morning's New York Times:
The Joys and Hazards of Self-Publishing on the Web
So what's your goal? Is it just to see your book in print (or on the Kindle or Nook or whatever)? Or is it actually to make a name for yourself as an author, possibly even earn a little money?
Sure, if you have a spare $5,000 or $10,000 burning a hole in your pocket, and you want to see your name in print, go for it. Most of us don't have that kind of money. In fact, many of us are living paycheck-to-paycheck or supplementing with nearly-maxed-out credit cards or sometimes even selling our own stuff on eBay (although in about an hour I'm going to discuss a job offer, for real -- as a 34-year-old with 3 bachelor's degrees and a PhD, I'm supposed to be in that full-employment group...but I digress).
You could do the Kickstarter thing and maybe come up with enough to pay for all the editing and cover design. If you go that route, I'd advise hiring someone to help you format your work for the various electronic distribution platforms. I once read that if you don't have a Kindle (or iPad, or whatever) and absolutely love it and use it all the time, then you're really not qualified to do the formatting of your own book for a Kindle. It's not just "press a button and everything magically converts," I gather. Although I don't have an e-reader so I don't know this for a fact. But I see a lot of complaints about Kindle formatting issues in Amazon reviews, so it is a real problem. (Especially in the early days, when there was a rush to put as many titles on Kindle as possible.)
My own manuscript has now been in the "black hole" for 59 days. Another month or two and I should hear something. If it gets rejected, well, on to the next publisher. (If it gets rejected 3 or 4 times, well, I've got some ideas or I can post a bit on Book Country and get feedback.) If it gets accepted, well, then, I'll have a team of professionals to help me make it a polished product on every platform, and a marketing team. Not that I expect to slack in the marketing area, but Twitter is full of small-time authors trying to self-promote.
Bottom line: if you want to sell lots of copies of your book, self-publishing is not the way to go. For every E.L. James, Amanda Hocking, or Michael J. Sullivan, there are thousands of people whose work doesn't get a bit of attention. Even if it is more deserving (at least in the case of James or Hocking...Sullivan was all right, at least).