Oof. This guy has been the biggest positive surprise of the US presidents in my lifetime. Expectations were low, but he actually turned out to be a good president (from a European perspective). No new wars, no more talk about shifting defense focus to Asia, generally nothing unreasonable. Good support for Ukraine, no doubts about NATO - rather the opposite. Basically, the rich uncle on the other side of the pond has been a good one.
I presume that his attitudes and staff selection carried the day, and maybe could have done so for another term. But his mental capacity was clearly declining, and he is in fact expected to handle some things personally.