First, we're now several generations removed from WW II - the last major assault on the world by fascism. The survivors of that conflict knew they did not want to live under Hitler or Mussolini (or Stalin for that matter, who was no better), and understood that democracy for all its faults provides the best chance at a good, free, and at least reasonably prosperous life. The contrast of the Soviet Union, not to mention the fear of it, was a constant reminder of the value of democracy.

Now, that contrast is gone and memories of what might have been if democracy lost in the '40s have faded. Younger people just take what they have for granted. And since 2008, many of them feel as though the system has failed them. We can only hope that a new spectacular reminder of the alternatives is not necessary, but if we get 4 more years of Trump, I think something like that starts to become more likely.