John,

DeSantis had an opportunity. Folk at Fox News had tentatively switched to him. DeSantis failed primarily because he was an UNLIKABLE candidate (especially up close). Haley failed to define herself and challenge Trump when it was too late.

On the Democratic side, Biden wouldn't get out of the way, and no one of any stature would take the risk to challenge him.

Biden and Trump needed each other. Biden elevated Trump by making him the centerpiece of his campaign.

As for people behind the scenes, Both Parties had a mixture of complacents and cowards.

Best.