That's my bet. People have, for years, tried to act smart, say, "He's always been an idiot!" Nah. Below average intelligence? Sure. But he really turned a corner in 2021-22 or so and now the roller coaster is off to the races.
He's come with 9,000 stupid, mystifying, illogical, evil even, statements. But yesterday was something I've never seen before. You and I would be headed for a rest home if we acted like that. Put that in the bucket with the last 2-years of lunacy, we would be living with a full-time caretaker if we were rich.
People like us that are watching and politically engaged have been noting the slide, but that performance yesterday was on display for a long time, not merely a sound bite a supporter can weasel around.