I wonder how did you arrive at that.
It's sort of common knowledge that only 1-2% of books written will net any sort of profit, so one might just as well write for free. As many, many people do, and outperform the for-profit writers too, on quality.
The only way to get to the point where you earn a living as a writer, or actor, or film maker, or painter... is to start off by doing it without getting paid. The fact that most people ultimately fail isn’t evidence that they’re not interested in succeeding.
Aspiring writers can aspire for fame, an audience, enthusiastic reviews, a platform, or loyal fans. Do those necessarily put food on the table? No, but many people happily write, perform, paint, etc. knowing that it won't pay the bills. The idea that everyone is in it for the money is a blanket statement that I'm not sure is even true for most creatives.
You can make a separate claim about whether artists should be able to financially support so that they can make art full time, but that's quite a different claim.
Citation needed. Writing a book, on average, makes people very little money. Some of the funniest or most entertaining content I've read has been on sites with user-generated content, such as Reddit, where there's no (direct) profit motive for good writing.
Profit motive or not, people will continue to write. Homer and Shakespeare lived in a time with no copyright laws and produced some of the greatest works of literature.
I'm not advocating for zero copyright laws, but I call bullshit on this assertion that creative works exist only due to their protection.