Thing is, while he might have done that before (I don't know and I'm not taking sides as I'm not an Elmer) why would he behave like that now? (Bouncing from one advisor to another, I mean.) The extent of his power can't be longer than 2 years because of the 2 terms rule and it's incredibly unlikely to be any less than 2 years, even if he sat on his ass and did absolutely nothing.
That's a good and reasoned question. I speculate that he knows no other way. He has for so long been in ballistic mode that it has now become natural and provides the path of least resistance. I watched his speech last night and I couldn't help but reach the conclusion that he was out of his depth. Although he fails at speaking extemporaneously, he is normally fairly good at delivering his messages when properly prepared. Last night was as controlled a situation as he is likely to find and his delivery, pacing, tonal quality and lack of any deference spoke to me about a man at the end of his limits.
I've always believed him to be a pretty darn good grifter but he let himself literally get carried away by the overwhelming and indomitable forces of Hollywood and Beltway exuberance.