I'm pretty sure he's bipolar. Sometimes he's calm and rational, but other times he just flies off the handle and does the crazy.
He has stated before that he has Asperger's Syndrome.
Elon Musk opens up about growing up with Asperger's
There are relatively few known examples of successful entrepreneurs and business leaders with Asperger’s.
"To anyone who I’ve offended [with my Twitter posts], I just want to say I reinvented electric cars, and I'm sending people to Mars in a rocket ship. Did you think I was also going to be a chill, normal dude?"

