The F-20 cost per plane radically ballooned such that it was canceled at low numbers making the unit cost even greater by reducing the number of planes to spread outrageous development and manufacturing start up costs over. The maintenance costs of both the F-20 and B-2 are both sky high to maintain their stealth characteristics.
As an aside…. In the Afghanistan War, the wings were flown off the B-1 fleet. It needs to be retired quite a bit earlier than would otherwise be required. I have read that some or all of the fleet is no longer low level, supersonic rated as designed for its role as a contested space penetration bomber.
Anyone please correct me if I’m off on any of this.
It may have been a technological marvel. I certainly don't have the ability to judge that.
But a "cost per plane radically ballooned" should be a major concern - and perhaps the reason to consider it a failure.
In WWII, we had the most advanced fighter (the P51 Mustang). Something like 15,000 were produced, at a cost, if you believe government inflation statistics, at about $800K in today's dollars.
THAT is a successful program!