I came here to say Dennis Rodman. But yeah, the point is that people as vile as Trump are not thin on the ground. It's not an accident that a relatively decent, intelligent guy like Barack Hussein Obama seems like a philosopher king compared to most occupants of the Oval Office.
Even George W Bush's commendably decent behaviour in the post-2008 transition stands out like a beacon in the bleak landscape of American presidencies. Nothing in his presidency became him like the leaving of it.
When thinking about "who'd be worse than Trump," you can't just think about his complete lack of inexperience, his disinterest in the job of president, utter failure as a negotiator, and constant, constant lying (even about things that are easily disproven the moment he says them). You also have to factor in his extreme narcissism and open disdain for anyone who dares disagree with him, or criticize him in any way. I think an Alex Jones type, with his level of crazy, might have a shot at being worse.
Roseanne and Kanye would give him a run for his money.
Someone like Hannity.
The argument can also be made that a more capable person who avoids all of the fuck ups that Trump routinely has, would be much more dangerous to the country. So, someone like a Stephen Miller, Steve Bannon, etc., a person who is just as or more nefarious, but doesn't have the massive self-delusion and personal flaws so he stays committed to destroying the country, as opposed to creating a new scandal every day.
Mitch is far more lethal where he is. He's clever enough to realise that any political fallout he may encounter in public is a price worth paying for pursuing his present highly successful policy of cramming conservative nominees into the federal judiciary, particularly in the Supreme Court. America will have to live with his legacy for decades after Trump is forgotten. Basic human rights will be up for debate, the rights of corporations will be secured.
In terms of being a terrible, stupid, unqualified, mentally problematic person, not many. But Trump's incompetence is currently our only and best defense. So anyone more competent or willing to take advice in this atmosphere will be bad. Therefore, everyone.
The question is how Trump would have reacted to 9/11 or a 9/11 style attack. At least Bush knew he should defer to the military to make the decisions once the war started. Imagine Trump with his "I know more than the Generals" shit.
Also, recall that Trump once said we should take some of Iraq's oil as compensation for our great work there (aka blowing them up). And he was serious.
I have no doubt he would have started the wars and made it even worse.