Emphasis on "was". It got cheaper from mass production to the point it's cost competitive even with aircraft like the Gripen.

Got cheaper from mass production, or because the massive sunk cost of trillions of dollars isn't factored into the unit cost? Those trillions could have been used to improve the military in more important ways, not to mention the country, which has failing infrastructure, inadequate education, etc.

I'm not sure why you think the sunk cost wouldn't be factored into the unit cost? Lockheed Martin (and them any other subcontractors) aren't a charity.