i think the comparison to spaceX isn't valid really. the technology contained within a fighter jet far outweighs that of a rocket. rocket science isn't exactly that anymore, but these newer fighter jets are pushing physics in pretty serious ways. just take a look at any f-22 demonstration. my jaw drops at the things it does, and that's just its flight capability. and the f-22 is even outdated at this point. rockets basically implement capability known for many decades. that being said, of course these programs are insane, including their budgets. for example, the f-22 has a total program cost of "only" $67 billion.