Brad Lightcap, OpenAI’s former CFO and COO, told staff on Tuesday he is leaving after eight years “to start something new.” Elon Musk gave a one-word reply when he saw the news of another high-level executive leaving OpenAI. Musk has had public spats with the CEO of OpenAI, Sam Altman, since he left the company in 2018. Why is Musk talking about OpenAI exits ahead of IPO? Musk’s reaction is the latest chapter in the rivalry between him and OpenAI’s Altman, as he builds his own AI company.