It became a Ferrari due to feature creep and an enormously complex and expensive technology stack. The F-16 is not a Ferrari and NATO needs a multirole single-seat fighter that is affordable to purchase and fly.
My most charitable view is the F-35 became a jobs program for Lockheed Martin and subcontractors. People were trained and (allegedly) useful technology was developed. But the price tag appears unreasonable by an order of magnitude, and this puts no accountability on the program management or people signing the checks.
As for arguments about technology trickling down from the F-35:
* The argument needs evidence. I've seen no attempt to identify the value of the technologies developed against the time and money spent.
* Too much time was surely spent on integration and one-off details specific to the F-35 platform, and this is sunk cost unlikely to be recovered in future platforms designed by new teams.