Which is why you'll generally see a lot of effort being put into the sucessful kickstarters. If a game developer cannot convince potential backers of their ability to deliver the goods, the kickstarter usually fails (See, for example, the Double Fine Adventure KS, or the Torment: Tides of Numenera one). In other words, in order to pull off a successful scam on Kickstarter, you'd have to actually build a presentation convincing enough to fool people into believing that you have the skills to successfully pull it off; this is kinda hard to do if you do not have a reputation as a developer.
Basically, when Chris Avellone says "I need money to do this game", I am willing to give him my money cos I know he's able to do it.
J. Random Person? Not so much.