"Only once the second price is being paid do you see any return on the first one."
So he agrees with you: you start getting the benefits as soon as the "second price" is being paid.
And I don't think it's quite right to say that the sixteen hours are the actual reward. They're the space in which some of the actual reward occurs, so to speak. You pay the price of using 16 hours of your time to read Moby-Dick. You get the reward of 16 enjoyably-spent hours, and also the reward of having your brain reshaped in whatever way reading Moby-Dick does for you -- deepening your ideas about friendship or obsession or sailing or whales, etc.
The 16 hours you have to spend are still a price, even though you enjoy spending those hours. (Some people enjoy spending money. They're still paying when they do.) The 16 hours you spend reading Moby-Dick are 16 hours you aren't spending reading The Brothers Karamazov or sleeping or doing lucrative consultancy or talking with your friends.