Here's the thing I struggle with: I think it is a given that Trump's base has shrunk, not grown.
There have been many "last straw" moments over the last 8 years, several of which were massive. His handling of covid turned off a lot of people. January 6th turned off a lot of people. The classified documents turned off a lot of people. His statements about the military turned off a lot of people. Losing Roe turned off a LOT of people.
On top of that, his denial of covid killed off a shitload of his most die hard shit eaters. And yet, from 2016 to 2020 he gained 9 million votes. Where the fuck did 9 million new voters come from?
16 million more people voted for Biden than Hillary. Presumably these people either liked Biden more than Hillary or despised Trump enough to vote against him instead of for him, 3rd party, or sitting out like they did in 2016. Presumably Trump's 9 million had to be made up of people who either hated Biden more than they hated Hillary, or gained a newfound love of Trump that they didn't already have in 2016.
So, in the 4 years between 2016 and 2020 elections we have 25 million extra voters. We can chalk roughly 12 million of those to population growth. If we generously give Trump half of those new voters, and generously pretend that a roughly equal number of people crossed the aisle (Hillary->Trump vs. Trump->Biden), that means at least 3 million people developed a new found love for Trump.
That's after hundreds of thousands of his most loyal supporters died from covid. I just don't understand how he gained voters after all that. It's not like he had the benefit of being able to blame everything going wrong in the world on a Democrat in the White House, he was in the White House...