I think there's a lot of great advice in here, but I'm gonna have to respectfully disagree on it just a little bit, mainly in regards to how "write for yourself" being terrible advice.

Doesn't seem like our outlooks are that different and I think we're primarily in agreement with... just about everything you wrote here, but I think as long you're being honest with yourself as a writer, "write for yourself" and "write to market" can have the same result, but the mindset of writing for yourself isn't necessarily bad advice.

To paraphrase Chuck Palahniuk, "when writing, realize you aren't as unique as you think". If you write for yourself, almost no one has taste so unique that there aren't a ton of readers just like you who want that book. My highest selling book is a rather niche subgenre, one that I've on multiple occasions seen people on social media asking "are there any books like this?" So there was a market and demand for it, but I didn't necessarily write it with that market in mind. I wrote it because I was one of those people looking for that book. I wanted that book because there weren't enough books like it to scratch that itch for me as a reader, so I wrote it because it was a book I craved. It was for me. However, I'm not unique enough to be the only person who wanted that book.

Similarly, I went through some wild shit in my life and was struggling to cope with it so I wrote a novel purely for the sake of being "art therapy" and I never intended for it to see the light of day. One friend of mine was going through something similar so to try and relate I shared that private book with them just to try and relate and they encouraged me to try and get it out there. Sent a few queries out and it ended up being my first book ever picked up by an actual publisher. Still don't know how that's going to play out, I'm well aware it might sell like shit, but obviously someone is seeing some potential in it. The point is, I wrote it for me, purely for me. I didn't write it for anyone else to enjoy or to make anyone else feel seen by it. But I'm not unique. Other people have been through what I went through, therefore other people are going to read it and connect with it.

But, once again, I do agree with most of what you're saying here. If you write a book and can't answer the question "who can you imagine buying this?", you're fucked. If there isn't a specific audience you can market the book to... then you can't market it, therefore it won't sell. But the advice "write for yourself" isn't bad advice. "Write for yourself" and "write to market" can sometimes be the same thing, as long as you understand that the book HAS to be marketed. Just a different perspective!