Many YC companies didn't need the money. We (Virtualmin) didn't (though it helped to offset the cost of my move from Austin where I had property to deal with and a car to sell--and the significant disparity in cost of living between there and here...I certainly didn't have any desire to turn down the money, but we signed on for the experience not the cash). pg has said about a third of companies don't need the money. The limiting factor is time for pg, tlb, and Jessica, not whether you need a measly 15 grand to survive long enough to launch.
But, frankly, nobody applies because of the money. There are cheaper sources of money.