It's hard to sell books. That's a simple truth. You can do everything right in terms of genre tropes, expectations, etc., and still have a dud. In some cases, it's a true mystery: the author will have a well-written story, a fantastic cover and a killer blurb...and the book won't sell a single copy. It's a real head-scratcher.
In other instances, however, it's plain as day why the book is struggling: the author will have done a terrible job on all three fronts - cover, blurb, and story - but will marvel at the injustice in the universe when readers fail to fight tooth and nail to purchase copies. In those instances, the author can come across as somewhat delusional in terms of both their sales expectations and how readers will react to their work. By way of example:
I have a friend who has written a book. I offered to help them with the self-publishing process since they had never done it before. I also offered to help edit it so that they wouldn't have to pay for that particular service. When I get the manuscript, it's essentially one huge block of text: no separation of paragraphs, no chapter breaks, no nothing. I tell them this has to be fixed. No, no...they'd rather just publish it as it is. I apply some arm-twisting, and they agree to put in some chapter breaks, separate paragraphs, and so on.
Also, when I first take a look at the manuscript, MS Word opens up a window I've never seen before - one that I didn't even know existed, in fact:
"This document has too many typographical and grammatical errors to continue showing them all."
Seriously. Once I get over my shock and surprise, I tell them all of this [feces] has to be fixed. No. no...they'd rather just publish it as it is. I apply some more arm-twisting, and they agree that that these are things that need to be addressed.
As I read the manuscript, I immediately notice that it's incredibly choppy - eg, characters will be talking to each other outside, and then in the very next sentence (not the next paragraph, chapter, or the like - the very next sentence), one of them will be in a restaurant, at the movies, in the can, or something like that, with absolutely no indication of how they got there, when they got there, why they're there, etc. (And no, this is not SF/fantasy, so there's no teleportation, materializing, and so on.) I point out the lack of transition in scenes and say that all this [mf'ing feces] has to be fixed. No, no...they'd rather just publish it as it is. ("Readers will understand what's happening," they say.) I again apply some arm-twisting, and they agree to address these issues.
Adding fuel to the fire, the story is rife with inconsistencies. For instance, two characters drive to a city in another state that is described as being at least two hours away by car; later, one of the characters states that the drive only took an hour. There are also a couple of siblings who, at the beginning of the story, are two years apart in age. By the time you get to the last page, the difference in age is seven years. I point out that these (and the many, many other inconsistencies) have to be fixed. No, no...they'd rather publish the story as it is. ("Readers aren't going to care," they say.) By this time my hands are [eff'ing] gnarled from all the previous arm-twisting, so I invent an arm-twisting machine and put my friend in it and crank it up to high. They agree to fix the inconsistencies.
I could go on, because the list of poor choices my friend wants to make in terms of publishing this book goes on forever. (For example, they initially chose a cover for the book that is completely unrelated to the story; in fact, the cover at issue would actually make a reader think the book was related to an entirely different genre.) They think that the things I've pointed out are much ado about nothing. My response was that we should publish the book - as is - but under a pen name. That way, my friend could see the kind of reaction/reviews the book gets and whether the issues I've highlighted are really of concern to readers. But no, no...if the book gets published, they want their real name on it, regardless of whether it's fit for human consumption.
In short, based on this experience, I've learned that some of us really are delusional. There are some authors who publish things that really aren't ready for prime time. They simply believe that the power of their story is so great that readers will overlook glaring errors, but (as we all know) that is simply not true.
More to the point, I think it shows a certain level of disrespect for the reader. Yes, readers are kind, generous, and willing to overlook the occasional fault if the overall product is good. But you can't just shove anything out there and expect readers to flock to it. They deserve better than that, and any author who thinks its okay to offer readers anything less than their best work really is delusional.