I'm personal friends with a number of authors who publish books in one of several subgenres. Mostly, they rely on Amazon's Kindle Unlimited: some of them are prolific enough that their book sales account for most of their income, simply based on peoples' reading of their works.
Mostly, unless people want a piece of history or something they can reference, folks seem to hate having clutter. Fiction that sells isn't usually, primarily sold as a hardcopy book anymore, I don't believe - short of the kinds of books that end up at the end of the grocery store isle or in an airport novelty store.
Regarding the OP topic, a lot of the published hardcopy books of the types mentioned are published for the explicit purpose of a PR or political campaign. Stuff like the Obama or Hillary Clinton books which are pushed massively and funded by third parties - the fact that they're books and people (supposedly) buy them is secondary, they're being paid for by other interests. They're basically a long form version of those "get published in our magazine about who's who/the top 50 in the x industry, for a low, low price of...." magazines you'll sometimes see, still.