[outworlder]

Is it just a budget game, though? How efficient is each country with their budget?

US spending one trillion dollars, and China spending one trillion dollars, it doesn't guarantee that they will be technologically matched.

It does not have to be symmetric. You only have to spend as much as you need to nullify an adversary's capability. Ex, one does not need to manufacture an aircraft carrier to counter one, you just need to take it out of action.