I think what Trump supporters don't understand, is, America had a great manufacturing industry following WWII because their factories hadn't been destroyed. It took Europe, Japan, and China decades to rebuild and recover. Only in the 1970s did it become apparent that Japan was going to eat America's breakfast in terms of cars and electronics.
The only way to make America "great" again (as a manufacturer), is to destroy India, China, Japan, and Germany through military conflict.