You're comparing apples to oranges. You've even stated this particular fact in your post with the paper example. You state that one should not chose a pricing

You're comparing apples to oranges. You've even stated this particular fact in your post with the paper example. You state that one should not chose a pricing strategy based on competition, but at the same time, aren't you validating your own strategy based on the earnings of a competitor? The comparison shouldn't be how much you made vs another book, what you should be comparing is how much would you make if you sold your book for a different price. What it comes down to is the basic economic theory of equilibrium.