The for profit entity is ultimately controlled by a nonprofit, kinda like how Mozilla the nonprofit also owns Mozilla the profit-seeking company. Patagonia (the clothing company) recent became something similar too.
The onion layers let the for profit subsidiary make some money and get taxed on it, but they are ultimately beholden to the nonprofit parent's wishes.
I guess OpenAI just expects to get a lot of donations / quasi-investments. Hell, Mozilla survived for two decades on Google's teat, and all they do is make a browser and act as a thinktank.
If OpenAI can keep up the momentum, there'll probably be funders lining up for new arrangements after the Microsoft one expires. Shrug.
But none of this explains wtf happened yesterday.