There's no absolute and objective measurement of "how good things really were." The appeal of Trumpismo arises within your blindspot, the patriotic feeling of being part of something "great." (I don't think the need and mechanism are absent from your character - or can be - but you experience them via displacement to a different concrete ideal.)
The Trumpian turn is to blame the browning of America and the Jihadi under the bed on the elites.
I disagree with you on many things, and wouldn't put it exactly that way, of course, but I think your first paragraph sums up the dynamic quite succinctly!
As for the second paragraph, I don't see things quite that way. "Conservatism" in Europe still means something - or some things - different than what it means in America.