Think of all the money you can make shorting the stock.
I suppose Elon would for some financial manipulation games to prove he is the richest, but otherwise seems like a bad deal.
For Musk, to stave off an embarassment. Same as the X acquisition into xAI and, most probably, the xAI merger with SpaceX. For his backers, to maintain access to the world's richest man.
Then there is the fact that Tesla operates America's only scaling EV-manufacturing operation.