"Writing a book is an activity that creates more value than it captures. What I mean with this is that the benefits that readers get from it are greater than the price they paid for the book. To back this up, let’s try roughly estimating the value created by my book."
This is the key - you need to create more value for your customer than you are asking them to pay you. If you do that, you will never be want for income because people actually value having you around. Otherwise, you are just a rent extractor.
This is the key - you need to create more value for your customer than you are asking them to pay you. If you do that, you will never be want for income because people actually value having you around. Otherwise, you are just a rent extractor.