Elon Musk's biggest regret in his life is probably teaming up with Sam Altman to co-found OpenAI. He later admitted that he could have made OpenAI a purely profit-driven company back then, but he deliberately chose a non-profit route focused on public interest. He funded it, recruited the people, and even unreservedly shared his entrepreneurial experience with Sam. As a result, this charitable organization was quietly taken over by Sam.