Elon can give them 400B and he would still have a net worth of 100B and from that he can again get back to his former net worth in a few years. The world is not fair.
> Selling 100B worth of stocks for anything close to 100B is not possible. That volume would mini-crash the entire exchange
Nasdaq trades about half a trillion dollars a day [1]. Even if Musk were an idiot and dumped $100bn in one day, it would crash Tesla's stock price, not the Nasdaq.
If Musk wanted to give OpenAI $100bn, the best way to do it would be to (a) borrow against his shares or (b) given OpenAI his (non-voting) shares.