A high-stakes federal trial begins Monday with Elon Musk suing OpenAI's Sam Altman and Greg Brockman for over $130 billion, alleging betrayal of the company's nonprofit mission. Musk seeks their removal from leadership roles. OpenAI, valued at $850 billion, dismisses the suit as baseless. Key figures like Microsoft CEO Satya Nadella and OpenAI cofounder Ilya Sutskever are expected to testify.