Because he actually believes in this! He's flip flopped on most issues over the years, but tariffs are something he has been really consistent on.

This is an ad he took out back in the 1980's.

(This should scare the s*it out of you.)

Meanwhile, most normal Republicans know this is pretty much nonsense, but they've either been kicked out of the primary or have been bullied into submission via the threat of getting a MAGA primary opponent.