It's more than just NASA funding, a large number of the top guys at SpaceX are or were ex-NASA engineers (or NASA contractors). It's no coincidence that SpaceX hq is where it is (in El Segundo literally next door to Northrop, Raytheon, Lockheed, and so on); it makes the hiring that much easier. SpaceX is what you get when you cut through all the bureaucratic bs which plagues the NASA organization and let the NASA engineers do what they know how to do. Brilliant stroke on Musk's part, gotta hand it to him.