If we're going to sit around waiting for the guy to commit genocide and start a world war before we take the threat seriously, it will be far too late to do anything about it. We need to look for leading indicators.
The tendency to treat Trump as inherently illegitimate and to ignore the voters behind him is just the kind of condition that might lead to future horrors. You might argue (though I wouldn't) that Trump's silliness is also such a leading indicator.
But so what? In a democracy both sides get their chance to push pull.
Case(s) in point: the FCC, FDA, minimum wage laws, Federal involvement in education.
None of those is Constitutional without some laughable legal gymnastics around inter-State commerce, and yet very few people have been complaining about their existence over the years.
As a non-American observer, the whole system seems reminiscent of ancient Rome at the point where it had become an Empire but was still pretending it was a Republic.
Take Obamacare as an example. Leaving aside the issue of whether socialised healthcare is a good idea, Obama had to circumvent the law by instructing the IRS to collect revenues via an executive order.
Is that really a precedent that should have been set? Even socialists should have been a little uneasy at the disregard for the Constitution there, but instead, the ends won out over the means, and it went ahead.
On the one hand it was the age of Organisational Man, who worked for big companies, or states more centralised than any in history. Indeed, with colonialism still not dead, a realist thinker might imagine that iron-fisted empires were the way of the future.
On the other hand, racism was still acceptable, not just among right-wing thugs like Hitler, but also on the left from the progressive eugenics movement, genocidal communist fantasists like H.G. Wells and plain-old to American bigots like Woodrow Wilson.
In those days it was fashionable for intellectuals to think that liberal-democracy was a has-been that could not organise well enough to Do What Needs To Be Done (and what "needed" to be done, was of often genocide).
It was in this cultural milieu that the Nazis and Bolsheviks rose and did what they did. Conditions like that don't exist in the West any more. I can see trends that might lead back to similar conditions -- but it will take a good 50 years for them to mature.