It's a good question, but also helpful to point out that one of the beauties of these models is that you can train them once and deploy to many use cases. The same model can be used by Github, Bing, Office 365, Azure and so on.

And as for the big multi-billion investment in OpenAI, they may have more than made that back up on their valuation already. Plus the deal was structured that OpenAI would pay it's revenues into Microsoft till the investment was paid back and MS would sill end up with a 49% stake.

All in all, sounds like a smart investment from MS and, cerry on top, managed to majorly embarrass a main rival.