Booming is a relative term. I would have to see how many writers are making a "living wage," a favored term of people in tech circles which generally means a fraction of what they make.
For creatives, however you care to define the term, probably. But there are a lot of professions where fairly run of the mill professionals and even tradespeople still make a pretty decent living even if they're not partners in their organizations or own their own businesses. Of course, you get down to the tier that's doing taxes at Walmart or working in an auto parts store, not so much, although probably still more reliable income than the average Substack writer.