You’re right, but it goes a little further than Biden being a familiar enemy. I think @aurora_maire nailed it in the 'Is trump confused?" thread-- it’s all about revenge. trump has long been vengeful toward anybody he sees as his enemy, and in his mind he was hoping to crush Biden, who he sees as having stolen the 2020 election from him. The desire to not just beat but humiliate Biden gave trump energy and focus (as much focus as he’s able to have, anyway). Now he feels robbed of his chance get back at Biden, and it’s left him listless and off-message. One of the main driving principles that keeps trump going is revenge. Richard Branson tried to warn us before the 2016 election.