This biggest most is high-quality data. Both their proprietary datasets (WebText, WebText2 etc), but also now their human-annotated data. Another secondary moat is their expertise with training models using PPO (their RL method), they can get results that are quite better than other labs. I say this moat is secondary because it's possible that you can get similar results with other RL algorithms (e.g. DeepMind using MPO) and because maybe you don't really need RL from Human Feedback, and just fine-tuning on instructions is enough