There's been a number of cases of people who could pay for their entire project out of pocket deciding to come to Kickstarter instead for the greater exposure. To date, though, I've never seen anyone be so blatant about it. On the one hand, KS has stated that this was intended as sort of an incubator for small ideas to become self-sustaining and not a marketplace, but on the other hand, those fees they rake in are probably a little too hard to ignore - hence, I haven't heard them whine about KS turning into a marketplace in many months now.
Basically, they don't care as long as they get their vig.