The F-111 was always useful in the role that the USAF wanted it for: light bomber. It's the USN role that it failed miserably at. And the experience gained from

The F-111 was always useful in the role that the USAF wanted it for: light bomber. It's the USN role that it failed miserably at. And the experience gained from the F-111 directly fed into the F-14. The F-35 program hasn't cost over a trillion dollars. It's supposed to cost over a trillion by the time they retire it, sometime 50 years from now. That is to say, over the 70 years that the program is expected to last, it'll have cost over a trillion. The F-35 is a replacement for the A-10 for CAS, but it's conception of how to do CAS is different, because we expect enemies that aren't just guys with a rifle to have the ability to hit stuff at low altitude. So we don't want to have our new stuff operate at low altitude. Literally every aircraft in the USAF/USN/USMC tactical fleet can do CAS in the way the F-35 is supposed to: drop munition from medium altitude. The F-35 is just supposed to be generally better at it (better sensor fusion, etc). Hell, we even have B-1 bombers doing CAS, by dropping bombs from medium altitude. The F-35 isn't supposed to rival or surpass the F-22. It's supposed to complement it.