Just like the "tesla hyperloop" or whatever they're calling it, it's not about innovation. It's about keeping his brands in the public eye as a form of marketing. Even if on a logical level we all know it's horseshit, it still keeps himself and Tesla salient.
He can afford to burn an incomprehensible amount of money on stunts for outcomes most people would consider inconsequential.
I'm not saying it's 4D chess, it definitely isn't. He's not particularly intelligent in that way. That said, I do think there are some very simple reasons for him to do this that go beyond his absolutely insane delusional ego.
He has enough money that he can continue funding whatever he wants regardless of public opinion. He literally exists at a level where any press is good press as it keeps him fresh in peoples' minds.