I don't think user submitted question/answer is as useful for training as you (and many others) think. It's not useless, but it's certainly not some goldmine either considering how noisy it is (from the users) and how synthetic it is (the responses). Further, while I wouldn't put it past them to use user data in that way, there's certainly a PR/controversy cost to doing so, even if it's outlined in their ToS.
In enterprise, there will be long content or document be poured into ChatGPT if there isn't policy limitation from company, which can be a meaning training data.
At least, there's possibility these content can be seen by staff in OpenAI as bad case, there's still existing privacy concerns.
