The low budget marketing channels that worked in the past are harder in this post-LLM world. SEO seems to have changed a lot, email marketing now involves trying to escape the Promotions tab, organic social media marketing is much harder too (I suspect the large social networks want you to buy ads, not get organic reach as a person/business promoting a product or service). Marketing something like a self published book online has changed dramatically.

You're not wrong, but you're sorta saying "the reason most people don't make money on Kalshi is because they're bad at gambling." Marketing matters, but most writers have no idea how to do it.

Maybe I am being too hard on you, but I think everyone who follows the writing world knows that writing doesn't influence sales. That's why publishers exist. Authors right now fucking hate traditional publishing with a passion—not just rejected authors, but career midlisters and lower-tier lead-title authors—and the only reason you don't hear more rage is that they know how replaceable 99% of them are. No one would put up with them if there weren't strong economic reasons to do so.

Most marketing strategies break even or have slightly positive EV for traditional publishers, due to all the entrenched unfair advantages they have. They're -EV for self-publishers who are trying to replicate the benefits of the stolen village on a shoestring.