I chalk it up to Trump not being a politician.
Many people say Pence is dull. He may be, but he showed what a good politician he was at the debate. He had a prepared articulate answer for just about every question and spoke slowly so the audience could take it in.
Biden did some of that during his debate, was able to articulate his points, came across as presidential at times. His 47 years as a politician paid off.
Trump had the winning arguments. He just didn’t spell them out very well, especially the Covid one. I thought Pence did a better job with that, especially pointing out Joe’s swine flu failure.
An example of Trump's thoughts' racing ahead was his response to Wallace, during the debate, when Wallace asked Trump (the loaded question): "Do you disavow racism and white supremacy?"
Trump replied: "Sure."
Wallace asked again.
Again Trump replied: "Sure," but, having answered satisfactorily, in his opinion, his thoughts had already raced ahead to another idea, and his replies--"Sure"--were soft spoken. A politician would have shouted the answers: "SURE! or "YES! I DISAVOW RACISM AND WHITE SUPREMITY!" which would have made an effective soundbite, but Trump, being an honest man and assuming honesty in others, and not thinking in terms of soundbites, believed his responses to have made his position clear.
Trump's dishonest and dishonourable (but I repeat myself) enemies intentionally ignored his responses--"Sure"--and, lying intentionally, claimed that he refused to disavow these things, though he obviously had done so.
His thoughts had raced ahead to a condemnation of those rioting and destroying American cities--something right and correct for him to do.
Trump's enemies twist his words, ignore the truth of what he says, to serve their own iniquitous purposes.
These lines come to mind:
Many knaves and fools are abroad in America today. Pray that they be outvoted in the November 3d election.