As another academic author who works in vastly different field, I can confirm this is true in all disciplines I have had the opportunity to discuss with colleag

As another academic author who works in vastly different field, I can confirm this is true in all disciplines I have had the opportunity to discuss with colleagues. It is common to pay a thousand and not uncommon to pay a few thousand to get something published, and the most that can be made from an academic book is in the same range. If I were to write for profit, it would be by writing a popularized version of a trending topic with far less academic value than a typical publication.