Two 22-year-old Gen Z students William Chen and Guan Wang, behind the open-source AI chatbot OpenChat, had rejected billionaire Elon Musk's multi-million-dollar pay offer to work at xAI, they told Fortune. Chen said they didn't want to work on LLMs as they "have their limitations". They then built a "brain-inspired" reasoning system that has now outperformed OpenAI, DeepSeek and Anthropic.