Everybody has an opinion as to why Trump received fewer votes in key states.
Trump, with no political positions, came in and pretty much made mincemeat of the career politicians running in the Republican primary, and he p/o-ed some serious “players” in the Republican Party. He then ran against Hillary, and we know the saga of the attempts at “Russian conspiracy” and the three years spent trying to find something with which to impeach him.
For some years there has been an increase on the “liberal” wing of the Democratic Party, and if one has been paying attention, there have been numerous reports of college and university students parroting a series of issues (“safe space” and “hate speech” among others, including mouthing slogans of the need for socialist policies without the slightest clue as to what the end result would be.
And there you have the makings of people who hate Trump.
Coupled with the antipathy well before his election, there are two other issues. 1) he had no political experience and 2) he has been a very successful businessman in New York. The two left us with an individual who for lack of a better term, did not “act Presidential” - he tweeted constantly; he trolled, he was abrasive, abrupt, rude, crude, and lacked most of the dignity of the office (with the exception of how he treated the military representatives coming and going - he knew how to salute and remembered to do so).
In short, even for people who strongly appreciated what he accomplished, he was an embarrassment; and for those who did not appreciate (or outright hated) his accomplishments, it further pushed their attitude toward him.
He also screwed up. I thoroughly understood what he was saying about needing to keep the economy going, but his treatment of the virus overroad his message that we had a fine line to walk between shutting down and spreading the virus more. in short, he did a crappy job of walking the line between capitulation to the virus and ignoring it. He was right about schools - and Fauci has admitted he (Fauci) was wrong, but Trump garnered no praise for how he handled it.
The debates may have moved a few people, but after 4 years, most people had their minds made up. And it is entirely possible that a lot of young people, who often do not vote, turned out to vote.
Was there fraudulent voting? Absolutely, but nowhere has it yet been shown that there was sufficient fraud to change the results; unless there was something really hinky about Dominion (which is still not settled) it appears he will not be sworn in come January.
What is clear is that nationally, the Blue Wave, which was going to flip governors, state legislatures, and the House and the Senate, flopped Which is another way of saying that, short of showing some massive fraud, people wanted what Trump accomplished, but did not want Trump - and that is not the same as saying that they wanted Joe Biden. Kamala is not a centrist Democrat, and likely was put on the ticket as a peace-making move to the radical Left.
