The candidate the social democrats wanted won and he's the guy who appointed Hitler chancellor! There was a three way race between "literally Hitler," "guy who will put Hitler into a position of power" and "not Hitler" (Thälmann) and somehow libs are still mad that "not Hitler" was on the ballot.
The social democrats were the ones with the brilliant plan of punching left in favor of a "center"-right coalition, and they actually won and got what they wanted and wound up in the camps as a direct result of it!
No prizes for guessing what happens when you trust the bourgeois parties to be an ally against fascism.