People collect historical memorabilia from all sorts of regimes, good and bad. It usually has nothing to do with sympathy for those regimes. As I said in another post, my dad’s old stamp collection included stamps from Nazi Germany; they were a reminder of history, nothing more.
And most people have a very superficial understanding of Nazism and Nazi Germany, which is why people throw around comparisons to Hitler and people buy it. I mean there are people who literally think Trump was Hitler.