I believe the idea is to support the “real” economy vs a “paper” economy. The “real” economy manufactures stuff in meat space instead of making value through abstractions like financial derivatives. The real economies are tied to a stronger middle class and national security. That’s the thesis as I understand it.

Because Conservative politics is about returning to a past that often can no longer exist.

The United States is current getting the base material for its entire economy from a country that is openly at war with it: China. If the US attacked East Tiawan because East Tiawan attacked Taiwan, East Tiawan would simply stop exporting rare earths, silver, steel, and electronics to the US. As a result the US needs to manufacture at home. So too does the EU.

I'll dig down 3 levels of "why".

The endemic anti-intellectualism among white communities (especially rural and southern) has resulted in a steady decline of white people in well-paying professions in America. If you count the Jewish as a separate group, white people are likely a minority in corporate America. Combined with social upliftment of other groups ("wokism") and the opioid crisis (that has disproportionately affected hinterland communities but immigrant groups seem immune to), white people are sliding down the American totem pole. Trumpism, alt-right, anti-woke, and the general resurgence of racist rhetoric are basically just reactions to all this.

These people want manufacturing because manufacturing is largely considered a "white people sport". If America becomes a manufacturing-first society, the hope is that it puts white people at the front and center of American society again.

JD Vance wrote a book about this.

It's not, they don't give two shits about workers, and their masters don't care how they make their money, just that they make it.

Manufacturing is just their preferred lie to get otherwise intelligent people to support their insanity.