If I was a Tesla investor my answer would be because that's what he signed up for when he took Tesla public.
What about the investors that want an unfiltered Elon and believe that’s part of the package deal?
If he's shooting for self-destruction and eventual reclusiveness, he's doing a great job. Seems unlikely that's his intent, though, and that's pretty much what's happening.
Maybe Musk and John McAfee can can retire to a Caribbean Island together.
All philosophical arguments are moot in his TSLA tweet. He broke the law. The question posed here is: Why?