The cost would be a very large chunk of OpenAI's business. People aren't just using ChatGPT just to solve problems. It is a very popular tool for idle chatter,

The cost would be a very large chunk of OpenAI's business. People aren't just using ChatGPT just to solve problems. It is a very popular tool for idle chatter, role playing, entertainment, friendship, therapy, and lots more. And OpenAI isn't financially incentivized to discourage this kind of use.