This election is between NOT Trump and NOT(NOT Trump). Before you point out that 2 "NOTs" cancel out, they don't in this usage. For example, a pear is a fruit that's NOT a grapefruit, but a fruit that's NOT a pear isn't inherently a grapefruit - it might be a blackberry.
Our first candidate, NOT Trump, happens to be Joe Biden, but it could be a rabid dog or a rotten tomato and it would still get a similar number of votes. Biden is a nice enough fellow. There's concern by some about his age and declining mental capabilities, concern by others about his occasionally sniffing about the ladies when maybe he ought not, concerns by still others about signs of corruption, and various other fairly mild personality concerns, but really, he's one of the most milquetoast candidates for president in quite some time.
But it doesn't seem that a lot of people are really that excited about Biden and really think he'll be a great President. Rather, they're voting for him primarily because he's NOT Trump. Again if it was a rabid dog instead of Biden they'd still be voting NOT Trump.
But how many people are voting FOR Trump? Some, for sure, but I suspect not all that many. I think never-Trumpers are a good example. One commenter here, PatrickH, claimed to be a never-Trumper, but said he was gonna vote for Trump this time around. At first I thought that was contradictory and certainly sounds contradictory, but then I realized he wouldn't vote FOR Trump but he would pull the lever (or punch the chad or whatever) for NOT(NOT Trump) and that it isn't contradictory at all! The fact that NOT(NOT Trump) happens to be Trump in this case is immaterial.
So what's so scary about NOT Trump that people would consider voting for NOT(NOT Trump)? Hardly anything really. EXCEPT! NOT Trump coupled with far left Democrats controlling all other branches of government scares a LOT of people to death. And when I write all other branches, I mean ALL other branches. It's believed, perhaps incorrectly, that NOT Trump with a democrat controlled congress will pack the Supreme court with far left judges that will strongly assist in completely remaking America, and not in ways that will benefit non-Democrats or Conservatives. Indeed, the belief of non-Democrats and Conservatives is that this remaking of America will badly damage their well-being in many ways from economic to spiritual.
Note that many of these beliefs about how they're going to be damaged may not be objectively true. But the NOT Trump party has done a poor job of allaying these fears and NOT(NOT Trump) has been able to exploit these beliefs to his advantage. Here are a small subset of the fears:
Religion: The vast majority of atheists and anti-religionists belong to the NOT Trump party and many of those do think that religion is a very bad thing and should be squashed as much as possible. For evidence look no further than the contentiousness of nominating Amy Coney Barrett as a Supreme Court Justice. She's Catholic and it's clear that the left believes that somewhat devout Catholics should NOT be allowed on the Supreme Court no matter what. If you don't believe that to be true, show me one at least somewhat devout Catholic that the left would accept as a Supreme Court justice going forward.
Manufacturing Jobs: While NOT(NOT Trump)'s foreign policy includes trade wars and border walls, NOT Trump's foreign policy is likely to be more globalist and more pro-China. While NOT(NOT Trump)'s policy may or may not have increased manufacturing jobs in the United States, it is strongly perceived by many that it did and NOT(NOT Trump) has very successfully exploited this perception.
Riots: Many who will vote NOT(NOT Trump) are watching with horror and fascination as Democrat run cities with Democrat headed police in Democrat controlled states burn because of riots (allegedly) caused by Democrat controlled police forces brutally killing black males. NOT Trump and the NOT Trump party have been slow to condemn the violence leaving many to fear that the whole country will burn if NOT Trump is elected. This fear is perception and not necessarily reality but NOT Trump and party have done little to nothing to alleviate the fear.
Abortion: Many people are very anti-abortion and want to limit it as much as possible. NOT(NOT Trump) has been much more supportive of their position than many of the NOT Trump party.
Systemic Racism and Other Wokeness: Many people greatly fear the concept of Systemic Racism, Critical Race Theory, White Fragility, etc. After all, the general concept is that all white people are racist (and therefore evil) no matter what. It's not surprising that not everyone wants to jump on that bandwagon. NOT(NOT Trump) has banned Critical Race Theory training for government institutions and that was very appealing to many.
And many more.
Again, all of these things are perceptions and fears as opposed to some cast-in-concrete objective future reality. But what is certain to me, is that the party of NOT Trump has not only done very little to address these fears and perceptions, but has in many cases actively stoked them and has "othered" those with different perceptions, goals and beliefs (for example, Obama's "bitter clingers," Hillary's "basket of deplorables," etc.). The problem with "othering" many tens of millions of people is that a very large "other" is created and they become the enemy.
And that enemy is voting for NOT(NOT Trump). Not because they like Trump but because NOT Trump is extremely scary to them.
Who am I voting for? Well, I endorse NOT Trump. Mostly because many of those I care about are severely negatively affected by Trump being president. For the most part, they're not directly or tangibly adversely affected, rather the mere circumstance of Trump being president badly damages their mental health and well-being.
If not for that, I might have been a NOT(NOT Trump) voter. After all, trade wars and border walls coupled with ever rising minimum wages is fantastic for a roboticist like me and I'm guessing I'll be thousands or tens of thousands of dollars richer if NOT(NOT Trump) wins.