I do think there is something to this. Not just that they spend allot of money consistently but consistently stick with a project to see it to completion. In organizations that I have seen lack of progress they jump from one fire to the next. This means that they work on A for a few months and then suddenly drop it to work on B because B is higher priority. Only to later realize that A was more important and switch back. DARPA having a large budget also allows them to see through projects to the end.