This is true of many, many careers: if you take that career in isolation, you could fund just the people in that career at their current salaries, for a tiny fraction of GDP. That doesn't scale to the entire populace, and there's no good justification for subsidizing this group and not others.
UBI, on the other hand, is entirely feasible, not least of which because it ditches the completely infeasible "at their current salary" in favor of "enough to live, not enough that most people won't want more". And you'd create substantial growth via startups and other creative endeavors. UBI gives everyone the option to try experiments that might not pay off right away.
A reason for subsiding this group but not others is that our economic system is so bad at utilizing the potential of their work.
It's literally free to distribute all books/newspapers/magazines to all people in the world. Why aren't we?
It's common to have state intervention in markets that are unable to utilize resources efficiently on their own.
About UBI, sure! The point of my comment was that this isn't a "fanciful overhaul of society" but a real possibility that could be implemented given some though and political will. UBI also fits that category, but is probably a bit more expensive and disruptive than financing authors.
I'm glad that the wages for teachers come from the government. Imagine a world with only private schools.
Same with books. Easy access to books was a huge contributor to the industrial revolution and especially Germany profited from weak copyright laws. Would you rather insist on your rights for a few coins more - or transform an entire generation?
How would you determine if someone qualifies as an author deserving full salary? Can I become an author by simply meeting a word count quota? What prevents a large portion of the population from quitting their jobs and becoming authors instead?
My understanding is that most bands make more on merch than the actual distribution of their music, because fans always want more and are willing to pay them directly to encourage more works.
There has to be a better way than the model we have now where everything is so tightly controlled.
UBI, on the other hand, is entirely feasible, not least of which because it ditches the completely infeasible "at their current salary" in favor of "enough to live, not enough that most people won't want more". And you'd create substantial growth via startups and other creative endeavors. UBI gives everyone the option to try experiments that might not pay off right away.