Take away all the obvious reasons why Trump is dangerous for the future of American democracy.
His abject lack of experience in government AND economics scares me a lot.
I've been through this in a microcosm. When I was 15, we lived on a bay. My father acquired a used Penguin sailboat. He never learned to sail but believed any idiot could figure it out (and I silently considered that he wasn't just any idiot).
One day, he ordered me (ordered!) to go out on the bay with him. I had refused as I considered it to be obviously dangerous under the circumstances. As my father was authoritarian, refusal was pro forma -- and dangerous. You didn't want to get him mad.
So I was compelled to put on a life jacket (those big orange ones) and go out on the bay. We got to a point 1/4 mile from shore when a gust of wind hit the sails. The boat tilted 45 degrees to one side, almost taking in water. And guess what my father did? He stood up and stepped on the side of the boat tilting toward the water. I watched almost in a trance as the water came in, covering my feet, ankles, calves, shins, to my navel. THEN my father had me get out and away from the boat which had completely capsized.
I was bobbing on the surface of the water, knowing without a rescue we had to swim back to the shore. I wasn't scared. I was frustrated that this situation was predictable and here I was notwithstanding. A boat came by about 10 minutes after the sailboat capsized and brought us to shore.
Fast forward to present tense. Symbolically we're all in the sailboat with my father who had no business sailing. The ill-at-ease feeling is that I don't believe serendipity will protect our economy, our environment, our hope for the future because Trump is in the White House. There won't be a "boat" to rescue us by way of either republicans or to a lesser degree, democrats (the latter if only because of no majority in either House of Congress).
I can wish that I'm exaggerating and I'm wrong, but my déjà vu is getting in the way of being optimistic.