Some things:
1) Biden was the best person to beat Trump in 2020, and so Democrats chose him. I prefered Amy Klobuchar, but I understood the thinking in 2020 to choose Biden. As progressive as Democrats like to say they are, they still aren't ready to give a woman a shot at the Presidency. So, not a mistake for the DNC to back Biden. We were in a crisis with Trump, and we had to put out the fire first and foremost. Biden did that. Yes, we're in a not-perfect situation now just because he's so old, but we had to get Trump out of there, and Biden was the best shot to do that.
2) You are correct about Trumpers, especially, burying their heads in the sand about the truth about Trump. He is facing all of the charges he is now due to grand juries and testimony from REPUBLICANS. This is no partisan witch hunt. Trump is a criminal and the law is acting accordingly.
3) As much as Democrats aren't ready to vote for a woman for President, Republicans are even further away from doing so. Haley has NO shot at getting elected President as a Republican. The fact that she's Indian American hurts her too with that bunch.