That's totally untrue. You clearly do not have any experience designing, building, manufacturing, testing, and certifying either cast metal or PBF parts. BTW, PBF is powerbed fusion and it is how you make 3D printed metal parts. FDM is a plastic manufacturing process and has nothing at all to do with replacing metal castings.

For a certain aircraft part that I designed, that measured approximately 16"x8"x10", if you needed up to 12 of them it was cheapest to 3D print them using powerbed fusion from AlSi10Mg, but with a 25% weight penalty due to the lower mechanical properties of 3D printed aluminum compared to cast. If you needed between 12 and 50 of them, it was cheapest to use 3D printing to make a wax preform then use the preform to make a traditional metal investment casting from A356. For more than 50 of them, it was cheapest to invest in permanent closed die tooling.

Other than for prototyping and extremely low volume production, additive has been a total flop for real-world manufacturing, and has not at all lived up to any of it's lofty promises.