I don’t know why anyone would buy an F-5 retread (F-20) when they could be mainstream and go with the F-16 or F-15.
Because it kicked butt. 2 Prototypes we lost to they think might have been G-blackout by the pilots which may have been a by-product of it's maneuverability. They took the two 4000 lb thrust J85 engines out of it and put one GE-404 "Trash Can" with about 20,000 lb thrust along with avionics cockpit upgrades and I think fly by wire. It was a Hot Rod, again like the YF-23, sometimes the best plane doesn't win...