Artists are able to work off of commissions, assuming that there is a demand for their art. (Getting that demand is the tricky part.) If people don't want their work on its own, then they have to work at a corporation - maybe making concept art, or drawing animation cels, or whatever. None of that art is owned by them; it's typically in the contract the artist signs when they become employed. Anything they make belongs to the corporation.
I used to work for Disney - in their theme parks, not as an artist - and even my employment contract said that any idea I had while Disney was my employer was property of Disney. Literally, if I had an idea on the job, I could not monetize it. If I thought of an idea for a video game or novel or movie, Disney owned that idea just because they were my employer.
Now. Could they enforce that? No way. But they could try, and as Tom points out then it doesn't matter if I'm in the write or not - Disney has expensive lawyers, I do not.
Scientists need grant money to do science. You have to convince a panel of experts that you have a good idea, and that your idea is worth throwing grant money at. Then you use that grant money to pay yourself and your assistants while you perform an experiment. This grant money can be from a university... or it could be from a corporation doing research and development for new concepts or ideas. If you make a discovery, the corporation might be able to patent that, since you were on their payroll at the time.
Making things Creative Commons doesn't magically make money appear. When you get paid by someone wanting to publish your work, they are specifically buying out your copyright on that work - they can do whatever they wish with it after. (Famously, this is why the first Harry Potter book is called "Sorcerer's Stone" in the US, because the publisher owned the copyright and changed the name.)
Creative Commons, therefore, is completely at odds with traditional publishing, since you can't sell your copyright to them. You can still self-publish, of course... but that's a whole can of worms. Not to mention that it's incredibly easy these days to have AI churn out 80k words of BS and sell it on Amazon for $1.99. You don't need many sales to break even.