Republican voters have been disenfranchised for many decades, Reagan said all kinds of wonderful things but he didn't so squat for the middle class, and every year since then the middle class has been further ignored while the GOP enriched themselves, defense contractors, oil companies and corporatists. Along comes someone like Trump, who smashed that mold and screams nationalism to his supporters, in the same way as other European leaders many generations ago. Find an enemy to blame for your problems (the media, Democrats, immigrants, regulations, etc.) and say that I am here to represent you, not wage war in other countries, not let black and brown people across the border, and I'm going to bring JOBS back to America.
Boom, you have these folks on a leash, and they'll never leave you, even if you're a pathological liar like Trump, who slashed taxes for the wealthiest Americans, cultivated a cult of fealty where only those loyal to him were allowed, job qualifications were inherently useless, and only getting the praise of his unthinking, gullible base was truly important to him. No jobs were brought back, even thought a media campaign was created to make it seem like they were. Guess what? You end up right back where you started with the classic Republican Party: The middle class, and those who vote for Republicans, were pandered to, and ignored, the focus of Trumpism was still centered on the wealthiest Americans, only the language changed.