Lots of them do and quite a few flounder in the "I'm working on it, sorry!" phase. I backed a project in early 2010 (A documentary) and the total raised was $15k, initial estimates were a few months. It's approaching 2 and a half years, the guy still updates monthly with "I'm editing this piece!" and "I did this" and sometimes he'll even include an excuse and apology!
I said it last year and I'll say it again now, Kickstarter is going to feel a serious backlash the first time one of the high profile projects falls apart because Kickstarter act like this big wonderful place for nurturing these projects and a lot of people seem to believe Kickstarter has some sort of interest in helping these projects succeed, but they don't, they are nothing more than a funding platform.
The problem is unavoidable I guess; give creative people lots of money, no guidance or supervision with only the moral obligation to actually do what they promised and inevitably quite a few will quit, change their idea or under deliver.
A common thing I've read on reddit is people believing that either Kickstarter makes the project creators accountable for not delivering or that the project creators don't get the money until they deliver... I wonder how a lot of people would react if they realised all they're paying for is a promise.
(oh and to clarify, I really do love Kickstarter and hope they continue to do what they're doing, but I can't help but disagree with their (potentially necessary) approach to projects after they've finished getting funded -- maybe they're working to solve this)
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I backed a project in May 2011 called "MemeFactory Writes A Book", billed as a book about internet culture. The idea was cute and I wanted a t-shirt so I backed it with $100. Now a year and a third later they've "changed direction" because their original idea "wasn't what they thought it would be" so here I am with $100 in a project that is never going to happen and instead I'm waiting on a new project... they also still didn't deliver my t-shirt. http://www.kickstarter.com/projects/rugnetta/memefactory-wri...
Another project that I didn't back but I'm aware of is by a Youtube video creator called Bashurverse, the summary is: "Donate to us to go to a convention and we'll make a documentary", they got $4k and went to the convention... and apparently got the $4k scammed from them by an evil company... so now they've not delivered anything and the people that backed them are left with nothing and thinking "...oh". http://www.kickstarter.com/projects/bashcraft/bashcraft-the-...
Will kickstarter do anything? Nope. Do people know that? Nope, they think accountability exists. When I now back a kickstarter project it's "I guess this would be nice to have, I'll send some money and maybe I get it, if not then whatever." instead of "holy crap this is amazing, I'll stick in as much as I can I can't wait!" which is how it should be.