See the thing is that for people to buy into it there must be a grain of plausibility. People do not automatically tend to fall for rank hoaxes and humbugs. People feared communism in republican Germany because they had lived through two failed putsches and Thaelmann was a rising force in the early 1930s, faster actually than the Nazis themselves were, so fear of a Thaelmann Putsch would have been very realistic.

Islamists? They're mainly a threat to themselves and no-one else.