I would assume people would capitalize their titles in posts since that’s the standard pretty much anywhere else like on YouTube or news sites, and that’s what you learn to do in school. Why is it only different on forum platforms like Lemmy or Reddit?
Book title capitalization should be used when the title is used as a title… which actually doesn’t happen all the time.
Your title right now is more deserving of a grammatically correct sentence, rather than a book title