Most companies that have open source products make their money in providing support for it to other companies, so theoretically OpenAI could do that (in fact top level AI developers are pretty rare so they could charge way more than other companies do for consulting) but that wouldn’t be a hundreds-of-billions-of-dollars business plan because it’s much too sensible.
My last tech job gave me a Microsoft Surface, which possibly explains why I was hired with the promise that things would be really busy, barely did anything for a year, and then got let go because there just wasn’t enough work to justify retaining my position.