Why is Trump the worst President ever, you ask. It's actually pretty easy to prove. Much easier than most proofs in my Geometry class.
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First of all, let's agree on this. With the exception of only a few Presidents, most are remembered for one or two things. No more...

Quick, name two things Calvin Coolidge is known for! Fuck it, name one. James Monroe is known for the doctrine, Herbert Hoover for the market crash.
50 years from now, Obama will be known for:
1) being the first black president,
2) getting health care passed.
Pretty much it...

Everyone loves Lincoln (well, except for our Great States down in the Real Americaland), but besides winning the Civil War, what else do you know him for? A few of you will know the income tax. Very few about the whole habeas corpus unpleasantness. Most won't...

You can even argue that LBJ is more notorious because he is universally known for 2 whole things: escalating Vietnam and civil rights. Truman is known for Hiroshima, also civil rights and a boom economy. Ike? Ike was nice.
So, with this in mind, let's look at Trump...

First, let's look at all the Great Accomplishments he and the cult love to boast about. The wall? If it doesn't fall down into the Rio Grande by 2025, it will be forgotten by 2026. The economy? Sorry, this shit's gone to trash with the pandemic. Trade wars? Already forgotten...

Jerusalem and the Great Tremendous Abraham Accords? Give me a fucking break. The Wonderful Very Talented Highly Respected Justices? Depends on what they do, but even so, justices are not remembered for who appointed them. Who appointed Taney? Who appointed Marshall? Nobody cares.

Likewise, you might hate Trump, but history won't remember most of his stupid tweets, his embarrassing behavior at the rallies, his constant lies and name-calling, the tax break for the rich, "shithole countries", "fine people on both sides" and defending Confederate statues...

Even the Russiagate and the Ukraine impeachment will be mostly curiosities for history buffs (like the Andrew Johnson impeachment, Teapot Dome or the Petticoat Scandal) than some universally acknowledged presidency-defining event, akin to Watergate...

And as much as I want the Summer of George Floyd to become a major watershed event in the history of US race relations, we probably have an extremely long and arduous road to cover on that front, with many, many more events like this ahead. So Trump's flirtation with racism? Par.

So, when your grandkids are sitting in their virtual Social Democratic Republics of America History classes in 2080, what they're likely to know about the Trump era is:
1) 100s of thousands died of a pandemic he badly mismanaged
2) he refused to concede and undermined elections..

And now, let's come back to our time and compare these two things to what the other contenders for the Stinker of All Time are know for.
Franklin Pierce? Utterly incompetent, spent his entire time in office drunk (had good reasons to, just check his family story)...

James Buchanan? Tried to protect Southern interests, contributed to the country's division, then sat on his hands to hand the bowl of shit to the next guy. Yeah, quite bad.
Andrew Johnson? An utter racist shit who wanted people to grovel at his feet and was hated by everyone...

Richard Nixon? Thought that presidents are above the law, was petty, vindictive and dishonest, resigned in shame.
George W. Bush? Started a war for bad reasons, OK'd torture.
I won't include merely inconsequential presidents like Fillmore, Van Buren, WH Harrison or Tyler...

But.
In the case of Nixon we have real, substantive, memorable accomplishments. Bush was great on one horrible day in America's history, and that day can't be erased from memory.
And with Bush, as well as with others, one other thing is undeniable...

They all, at the very least, believed in something greater than themselves. They could have had extremely terrible beliefs, but at least they did not personalize power to the terrifying extent that Trump has. Which is much, much worse than simply having a shitty worldview...

He's treated every issue, every assessment of every crisis and every personnel move based on what it does for him personally.
Trump mismanaged COVID not because he believed wrong things about how the pandemic works but because he made it about his own reelection chances...

Trump made his entire presidency about proving how great his was to his own damaged ego, to the ghost of his daddy, to New York elites who have always despised him, to Obama and to tragically deluded yokels who just loved how he hated the "right" folks...

Trump is the worst president ever because he was never the President of the United States. He was the Supreme Commander of His Own Fucking Demons. It was all, all of it, every single thing, every second of the way, about him. About making him feel great. All of it. As we died...

He's undermining our democracy not because he worries about election integrity and not because he cares about what happens to the country under Biden. He's simply lashing out because the country refused to affirm his own delusions of grandeur. The asshole was dreaming of Rushmore

That's truly it. Nothing more. Nothing more is needed. For the first time in history, the nation has not only elected a person who was unqualified, dangerous and immoral, but a person who was the absolute polar opposite of what a President should be.
Nobody is close, frankly. Fin