This has been a personal bugbear of mine for ages.
The F-35 and its predecessor the F-22 are planes that were literally built for no clear mission other than if the
Air Force doesn't spend its budget on a new super-plane it gets less money the next time around.
It took a decade and billions to get the F-22 off the ground only for the Air Force to decide that they needed a whole new type of super plane instead.
And the F-22 is downright cheap compared to the F-35. Mind you, there's was nothing wrong with the F-117 Stealth Fighter of all those 80's flicks. It's not like other countries developed better planes and we had to catch up.
The Air Force just wanted NEW Stealth Planes is all. Every other allied country is still using a variant of the F-15. We still make F-15s. We just sell them to other countries now.
This is part of the reason why there is such a bitter rivalry between the armed services at its highest levels. The Air Force and Navy can always justify its insane budgets by ordering new super-planes or Aircraft Carriers but what the army gonna ask for?
Tanks don't have sexy gimmicks like Stealth or Nuclear Armaments. So they get way less than the Navy and Air Force.
We can't get Health Care or an Infrastructure Program or a Jobs program, but the Air Force can get trillions for planes that it objectively doesn't even need that will take ten years to get to work and be in service for maybe that long.