But I believe since a ToS isn't a copyright license, this can't really be enforced using copyright laws. Most likely they can ban you. Is there even a slim chance you could be sued for breach of contract? Hell if I know, I'm not a lawyer.

Thinking another layer deep, though, if someone used OpenAI tools to develop software that then later got used to compete with OpenAI, surely it would fully workaround this already unenforceable ToS restriction anyways, right?