Elon's definitely not crazy, but he is impulsive and emotionally fragile, and I think he enjoys being subversive. This works both for and against him.
PayPal, SpaceX, Tesla, and The Boring Company are all based on subversive ideas. PayPal revolutionized online payments by subverting the norms of the stodgy banking industry. SpaceX revolutionized space launch technology by embracing reusable rockets made from low-cost off-the-shelf components. Tesla subverted the car industry by making all-electric cars that looked great, drove well, and got better over time through free over-the-air software updates just like cell phones. And The Boring Company is trying to subvert the norms of transportation infrastructure by expanding transit through inexpensive underground tunnels rather than above-ground roads and rail.
But Elon also has trouble not speaking his mind, and for a powerful man he's surprisingly emotionally vulnerable. He cares deeply about what people think of him and his companies. I think he thinks highly of himself and his accomplishments, but also has a deep well of self-doubt and anxiety. When people attack him or challenge his view of himself, he tends to lash out. And because he invests so much of himself in his companies, he takes criticism of them personally.
What's interesting is that when criticism comes from a place of good intent — such as a Tesla owner tweeting him and asking him to improve something they don't like about the car — he typically responds humbly and graciously. If you read his replies on Twitter, you'll often see him engaging positively with Tesla owners in this way, and it's really interesting to watch.
This is why I don't think Elon is crazy. If he were a complete narcissist or a sociopath, he would have a much harder time accepting honest criticism. But he actually seems to like criticism when it's truthful and well-intentioned. If it seems (in his judgement) dishonest or backed by an ulterior motive, though, he overreacts and lashes out.
I think the controversial "taking Tesla private" tweet that the SEC is now investigating is one example of Elon impulsively giving in to his desire to subvert norms and hit back at people — short sellers — who he sees as unfairly attacking him. It's not smart behavior from a CEO, but it wasn't completely crazy either.
That was Elon strolling right up to the line and then taking a little step right over it and daring the world to do something about it, because, for better or worse, that's what he does.