We are obviously stricken with huge egos. What, after all, is more egotistical than thinking that other people would want to read what you wrote? And beyond that, that people would be willing to pay their own good money to read what you wrote. What arrogance! What self-delusion!
But people do exactly that. As a reader, every author has paid his own good money to read the writings of another person. And people will pay money to read what you have written. Not just friends or acquaintances, either. Complete strangers are willing to shell out cash for the chance to read your writing. Wow.
And yet, we suffer from the scourge of chronic insecurity. If we become rich and famous and it seems like everything we write is gold, maybe we can slough off that insecurity a little. I don't know--I'm nowhere near that place yet. But for most writers, there is no security. We are constantly haunted by the fear that no one will like our book, our story, our memoir, or the magnificent revelations we have shared with them. Even though a publisher has deemed our work worthy of their time, effort, and investment, we can't get away from the suspicion that it isn't really very good.
The positive responses are never enthusiastic enough. Any tepid or mediocre reaction is a condemnation of searing severity from which we may never recover. Months or even years after publication we'll wake up one night, or it'll smack us unawares in the middle of the day and we'll curse ourselves with, "How could I have failed to include that?" Or, "Why did I leave that in? What was I thinking? No wonder nobody wants to read that crappy book!" If the book has been published by a professional publisher, there's little we can do. Maybe we can convince them to make those changes...and maybe they won't.
If the book happens to be self-published we can actually fix those horrible errors. We can take out that suddenly offensive (to us) sentence, or include that tidbit of information that we'd forgotten. And then all will be better. Until the next midnight wakefulness reminds us of another imperfection; or worse, that we realize that those change we just made were a huge mistake.
There's only one thing to do. Get our butts in gear writing the next book, or story, or memoir. That might not work, but it's the only thing that can.