I disagree - consider real estate agents: the buyer's and the seller's take home a total of 6% of the purchase price. If you were an agent, would you settle for, say, 300k, and take your 9k in your pocket, or would you fight a great fight to get to 310k? Commissions should be, in this example, zero until 270k, and then a big chunk of anything above that, to really incentivize the agent to do your best interest. Same for book agents. I self published two books for this reason. To be clear, I'm not saying that agents are ALWAYS bad. I am only saying that commissions are not designed to serve the author's best interest.