In the debate over "vaccine passports," I detect an implicit belief on the part of those who express outrage at comparisons of the scheme to e.g. requiring Jews to wear Star of David patches in Nazi Germany.
That implicit belief is that the Nazis didn't actually get high on their own supply -- that they were just snake oil salesmen who concocted a crazy sales pitch for the purpose of exercising power, then did so in a genocidal way because ... well, just because.
Oh, I'm sure there were some mere opportunistic hacks who didn't really believe in the Nazi pronouncements on race, etc., and just grasped those pronouncements as rungs up the ladder of power when they otherwise would have found different rungs. Goering, probably. Goebbels, maybe.
But so far as I can tell, others -- Hitler and Himmler, for example -- really, really, really believed their own guff. As did millions of their followers and supporters.
Ditto the early 20th century proponents of eugenics in, among other places, the US. And the early 20th century proponents of Marxism in, among other places, Russia.
And all of them, of course, loudly invoked "science" as a basis for their beliefs.
Con artists are dangerous, but not nearly as dangerous as people who really, truly, honestly believe in something, and who believe that that something is so important that it must be implemented even if implementing it requires the use of state force to impose it on the unwilling.
"But they really believe it" is not a sound criterion for trusting anyone with the power to force their stated beliefs on others.