My hypothesis is that many high-level Trump sympocants believed that they could somehow manipulate Mr. Trump. And that is how they would effect their agenda on the USA.
Mr. Trump has proven time and time that he may be simple, but he is not malipulatable.
Mr Barr had this knowledge before he took the job. So I have to wonder how much Mr. Barr believed his boss could really win or steal the election.
I believe Mr. Barr built a good reputation in the Bush 2 administration. It is gone now. But he has had a good run in politics and will retire in a comfortable financial position.