The issue with beer hall demagogue is that their rise has been made only while the society at that time was so devastated in every sense (morally, economically, ...) that people saw them as the only hope against the status quo.

That's the moral of the story: if the present is so bad, and the elites refuse to change anything and just go push for their agendas against the will and the interest of common people, common people will support the devil himself if he is the only one promising he'll do something different.