Chapo rubs plenty of people the wrong way for plenty of (valid!) reasons, but the Christman/Wade sub-series Hell of Presidents explores the evolution of the office and party systems, and this is one of the basic throughlines: When you hear "small-business owner," find & replace with "yeoman farmer"
I think it has to do with the type of capital rich people in poor areas have. Trump's base is the local gentry; landlords, car dealers, owners of small- to medium size regional firms. People who have money, but aren't plugged into same educational and social networks as rich people in cities.