You can't really do that with kickstarter because you don't know if you will really get the money from each supporter.
Due to this, and due to the fact that you need to be an American company (which can be gotten around, but is annoying) we decided to go it on our own with something that was very similar to kickstarter, while not actually using their service, which you can see here: https://www.pathofexile.com/purchase/
Using stripe.com for credit card processing, it was fairly easy to get payment processing up and running.
Really the reason to use kickstarter.com is as an advertising platform. I'm not really sure if having their audience as well as our own would have benefited us in this case or not.
As to paying money for just a concept, it's not really unlike the decision investors make on a smaller scale. Bear in mind that copies of a game on kickstarter are typically lower than the final retail price. Your reduce your risk by "investing" in a diversified portfolio of kickstarter games in the hope that one will turn out to be a gem.