almost all of it, yes. But if, for instance, your project is something that actually requires a $50,000 expenditure, and you put in the last $5000, then you now have a commitment to deliver your $50,000 project and only $45,000 to do it with. For some people that would not be a problem at all, they have that much spare cash. For others this would mean they need to go and fundraise an extra $5000 outside of Kickstarter.

Exactly. The other factor, obviously, is that you have to already have that $5000 and be able to part with it for a while. It doesn't matter that you get it back if you don't have it in the first place.