What equity?

The "there was no equity, because it was a non-profit" argument is stressing the term.

At least Microsoft thought it bought something for $13B.

When a wealthy person gives a museum much money and get a seat on the board of trustees - does that also mean that they "bought the museum"?

They didn't buy nothing. See things museums and institutions will do for wealthy donors, that they won't do for anyone else.

I'm not saying that wealthy donors don't get anything. Wealthy donors don't own the museum, just because they provided funding to the museum.

Just as wealthy donors to medical research don't get to own the results of the research their money funded.

Just as Microsoft doesn't get to own a part of Linux, for donating to The Linux Foundation.

Etc...

OpenAI is definitely on the "less" side of charity.

"OpenAI PPUs: How OpenAI's unique equity compensation works"

https://www.levels.fyi/blog/openai-compensation.html