Dictators need collaborators too, as far as I know. I can't imagine anyone single-handedly taking control of a country's government and operating it without help.
> A bad president needs collaborators to ruin a country
collaborators? trump seems to have a good supply of such collaborators
how trump got the Muslim ban, transgender ban, quit Paris agreement. oh, let's don't forget his ongoing efforts to build the wall, kill the public healthcare, stop global trade...
US democracy is nothing else but free Internet entertainment
He'll be gone in a few years, and those things didn't ruin the country (contrary to popular belief). It just ruins the reputation. And that regularly resets at the next election.
What really ruins the US is the large amount of apathetic people who don't actually care enough to vote or participate in civic duties.