Oh I've heard that. The classic "third book" being the one that goes viral. (Gillian Flynn, Dan Brown, etc.)

I agree with you on considering most books (most books don't market), but even trying to learn from the successful books isn't entirely encouraging. Even the best ones don't see a lot of reads.

But the industry is rapidly changing. We don't all watch the same three television channels anymore. Niche content is more the norm than mass marketed content.

I think the whole "creator economy" is still in its infancy, and we have yet to see whether it will actually allow creators to monetize in a meaningful way. But it's worth engaging with it as an experiment to see what happens!