He has always been far less coherent than most people seemed to realize, but I think he's getting worse. As I wrote earlier (or may have just thought I wrote), people are finally seeing enough of Elon Musk all in one place to finally recognize that he's an unhinged weirdo. It doesn't help that he's out of his prior element in which he could at least do a Silicon Valley style technology pitch. But the notion that a tech-bro bully is automatically also a general-purpose genius seems to have run its course for Musk.
As stated, we know he indulges in cannabis and ketamine. But on the narrow subject of drug use, it could be the converse problem: perhaps he has previously relied on them to keep him on an even keel and is now finding they don't work as well. I have a friend who has cut back on his recreational cannabis use, and I have noticed him being less coherent now than when he was partaking of more.
But as long as we're speculating about cause, it could just be plain old stress. Musk's wierdness may be the cause of his ejection from the Trump inner circle, but that causation may be operating in reverse. Without Pres. Trump's legal protection, some of the things Musk has done can still get him into a lot of trouble for which he will be personally liable. Not that Musk can't afford good lawyers. But he can't necessarily count on a Trump pardon anymore.
Plus it has now been reported that Tesla stock is nearing the margin call price. Keep in mind that Musk's purchase of Twitter was financed using his Tesla stock as collateral. If that drops to a certain value, Musk's creditors can seize it and liquidate it to protect its value as collateral. And they can also foreclose on the loan. Musk is facing the very real possibility that he may lose controlling interest in both Twitter and Tesla, and the vast basis of his personal fortune. I think the stress of this may be affecting him as well.
I also consider him a bully, if that matters.
You can still disapprove of someone while acknowledging that in some cases they can act in their own self interest in a way that also has a broader benefit. If the Trump administration jettisons Elon Musk, then I think we'll all be better off having Musk somewhere he can't do as much damage to the rest of us. But there will always be more idiots and opportunists. Donald Trump is not a smart man, and he handles this by surrounding himself with sycophants and idiots who won't call him on his nonsense.