He knew

The question still seems to be out there whether Trump actually believed he won the 2020 election.

[New York Times reporter Maggie] Haberman’s book, titled “Confidence Man: The Making of Donald Trump and the Breaking of America,” will be released early next month.

[...]

Haberman writes in her new book that Trump in the immediate aftermath of the election asked advisers to tell him what went wrong, telling one adviser “we did our best,” CNN reported, adding that he also told junior press aides, “I thought we had it.”

  The Hill

Let's get those aides on record before the January 6 Committee.

But later, Trump reportedly began expressing his intention to not leave the White House in January 2021 upon the start of Biden’s term as Trump’s team began attempts to overturn the election.

“Why should I leave if they stole it from me?” Trump asked during a conversation with Republican National Committee Chair Ronna McDaniel, CNN reported.

Somebody convinced him HE could steal the election, and he believed them.

Also, fuck Maggie Haberman who, like so many others, held onto material information for a book when it would have perhaps put an end to the nightmare we're living a long time ago.

...but hey, do what you want...you will anyway.