OpenAI don't monetize the vast majority of their users yet. But the unit costs are really low, and once they start monetizing the free tier with ads, they'll be wildly profitable.

"OpenAI cannot actually afford to pay $60 billion / year" the article states with confidence. But that's the level of revenue they'd be pulling in from their existing free users if monetized as effectively as Facebook or Google. No user growth needed.

And it seems this isn't far off, given the Walmart deal. Of course they'll start off with unobtrusive ad formats used only in situations where the user has definite purchase intent, to make the feature acceptable to the users, and then tighten the screws over time.