It’s older books not Netflix that’s the real competition. Amazon’s unlimited bookshelf holds a lot more than just Lord of the Rings. That said, residuals are also much easier to capture now days than back when book stores had extremely limited shelf space so it’s not all bad. There is a real trade off of fewer sales in year one but more sales in year 2-20.

On the numbers side people have a lot more disposable income, capturing a larger share of revenue per person can completely flip the equation. Patreon, etc don’t have to individually provide enough to live off of as long as all revenue streams add up to a living wage. I suspect if the objective threshold is say 50k USD inflation adjusted, today is relatively speaking a much better time to be an author than most people here are assuming.

Of course that’s ignoring all the vanity books being published. Simply having an ISBN number doesn’t really mean anything in today’s world.