[saiya-jin]

Well, low hanging fruit is sometimes hanging very low, but if you want to move past that and reach higher, it gets exponentially harder and thus more expensive.

Also things like reliability, durability under various extreme conditions, safety for humans involved and so on can escalate times and prices dramatically, but are not massive concerns in existential situation Ukraine currently is in due to russia's war.

US is basically never aiming so low with new tech they want for its military, it wants brilliant solutions above everybody else, and has money to burn on it. And from time to time, when looking back those investments were well worth even with flops included. US global hegemony is not something that US wants to lose due to few hundreds billions not allocated as effectively as possible.