> But where do those voters get their beliefs?

Conservatives have been threatening to drown the federal government in the bathtub since the 1980s. There’s no new beliefs. It’s just a reshuffling between the parties of the same folks that existed in 1990: paleocons and social conservatives, capitalists, neocons, nationalists, economic populists, etc. The anti-vaxxers were there, they were just democrats because that was the low-institutional-trust party back then.

The people you’re calling “Russian agents” were also there in the 1990s, as were the neocons calling them that. They just took over the GOP because it turned out that the Democrats (back then) were correct and american military intervention in places Iowans can’t find in a map is actually bad for the GOP base.