That they make money incidentally to that is really no problem and a positive because it provides reasonable funding.
What if Firefox made a world beating browser by accident. Would they be justified in closing the source, restricting access and making people pay for it?
That's what OpenAI did.
If OpenAI Co. is gatekeeping access to the fruits of OpenAI's labors, what good is OpenAI providing?
Concisely, in any human matteres: Do what you say you'll do, or, add qualifiers/don't say it.
Take funds from a subset of users who need support services or patch guarantees of some kind, use that to pay people to continue to maintain and improve the product.
Their sell-out path was hundreds of millions of dollars from GOOG to make their search engine the default, and, unspoken: allow FF to become an ugly, insecure, red-headed stepchild when compared to Chrome.
Likely part of what took priority away from Thunderbird, at the time, too.
I wish they hadn't because they are thinking too commercial (extremely high paid CEO) for instance but they have a foundation to answer to which doesn't manage them like shareholders would (eg not rewarding the CEO for dropping marketshare!). This model is the worst of both worlds imo.