“The value has to come from somewhere.”
So true. As you know, Kindle Unlimited collects a pool of all subscriptions and then pays out to authors based on an algorithm that takes into account the actual number of pages read. That model, although seeming logical by most measures, squeezes margin out of the author and the publisher. In the end, the author is choosing between discovery and revenue when they jump into that arrangement. The publisher on the other hand is generally worried about cannibalizing unit sales.