Take a look at this polling map. All of the brown states is where the polling is within the margin of error 5%. Then look at the electoral college. Trump has to pick up ALL OF THOSE and then more. Biden can lose all of those (but let's be honest, he probably won't lose Penn) and still wins. He only has to pick up 1 to shut the door on Trump. If he loses all the toss-ups, he still wins.
And if you're all "bu bu bu but 2016!" The polling wasn't wrong. It projected Clinton winning the popular vote- she did. And the races in the 3 states that Trump won unexpectedly? The polling was in the margin of error for 2 of them. Wisconsin being the outlier. Trump has spent $800 million in digital and tv ads, and the map looks like this.
If he was such a great president, if everything is going so great, the map should be a sea of red. But it ain't.
He's gonna lose.