The companies that are funding games through Kickstarters don't have the overhead that normal developers usually have. The money goes towards paying actual developers as opposed to marketing execs and other leeches that don't particularly add anything real to the game. A game doesn't have to sell five million copies in three months to be a success. If chaining Kickstarters is how a company wants to develop their games then one project feeds into another without the constant need to fire basically everyone at the end of each development cycle. This idea is epitomized by inXile Kickstarting/developing Wasteland 2 and when the art department/concept developers were finished with that game, they started a new Kickstarter for Torment: Tides of Numenera (a spirital successor to Planescape: Torment). Both of these games are pretty big and even the overpriced beta for Wasteland 2(I think the finished game is going to retail $25 cheaper) was on the top ten list on Steam for two weeks. Torment was (is?) the new #1 most funded video game (during a Kickstarter campaign), so there's a clear demand there.
Star Citizen is the game to watch with crowdfunding though. While not pulling in as much as Torment during the Kickstarter phase, it has since pulled $38,544,192, proving that these games can rake it in. They claim that the entire budget is split between something like four studios in different countries working on all the crazy shit they've been promising (first person planet-side and space-side combat, a single player campaign, a persistent multiplayer universe, etc.). While it's probably not going to be vaporware it's definitely a contender for "Why would we work really hard on this when we've already made tens of millions of dollars?" Seriously, people are paying $10s and $100s of dollars for microtransaction spaceships in a game that doesn't even fucking exist yet. I'm all for supporting game developers doing new things with more carrot (crowdfunded money) than stick (internet comment hate), but seriously let them finish the five million dollar carrot before throwing 35 million more at them.
These games aren't only being sold to people who are pledging and even if they were you could conceivable keep a company alive by chaining crowdfunded games together. They aren't trying to make games that are blockbuster successes (although in the case of games like FTL when you only have like 2-3 people developing something, you're basically an overnight millionaire). God only knows where I read the quote, but one of the inXile/Obsidian Entertainment guys just straight out side that they aren't trying to make big games that sell to millions of people. He wants to make the games he wants to play and he's flattered as all hell that people are willing to pay him to do that. Because the publishers sure didn't and when they did they wanted to change things and fuck it all up.
I think this stuff shines when you've got a smallish team of people who don't mind toiling in obscurity in order to make a game that probably won't make a big splash. These are people making cult classics. While I Kickstarted the shit out of stuff like Wasteland 2, Torment, and Project Eternity a lot of these games (Banner Saga, Broken Age) make my "Must buy when it goes on sale" list. A lot of these games fall into the "This was... pretty good" opinion in games (see: Shadowrun Returns, another Kickstarter game that has since been released to reviews that all seem to agree "It's okay") where if you don't already fall into the particular niche the game belongs in, then the game isn't going to knock your socks off.
Also I went ahead and threw my hat into the ring for this particular Kickstarter for $20. Good luck. But they probably don't need it since it went up $2,000 as I typed this post.