Well, the question isn't what OpenAI's intellectual property is worth right now, or what you expect it to be worth, but what it is likely to be worth after OpenAI has become insolvent (and few/none of the current employees are working on it). The most likely causes for it becoming insolvent are probably that another company out-innovates them, or that the revenues never come in (despite OpenAI being a market leader). In either case, OpenAI's IP is unlikely to be sufficiently superior to the competition's to warrant a large premium.

I am not sure how differentiated OpenAI's IP is, so I don't have a strong opinion, but it seems to me that OpenAI is worth a lot more as a package than it would be as a collection of pieces.

If even a singular open source model surpasses OpenAI's models between now and then then OpenAI will be worth 0 dollars, IP included.

Well maybe the employees will be worth something.

Their web-application is worth $200,000. The software of the training infrastructure is worth perhaps $2M; the inference infrastructure is worth perhaps $500,000. Their hardware is worth nothing in 3 years. Their B2B relations are worth perhaps $5M. The "data" they have is worth nothing in 5 years, because a sufficiently smart model will be able to learn without human feedback.

They have no moat. So, how do you get to $4B?

I think the models are wrong way too often for relatively simple queries, so unless they give a secret prompt like "be wrong a lot in the free version" to users, it's basically worthless.