FWIW, in the case of Eliezer's book, there's a good chance that at the end of the day when we account for all the related expenses, it makes very little net profit, and might even be unprofitable on net (which is totally fine, since the motivation from writing the book isn't making money).
This is such a tired take, and I can assure you it's wrong. Think what you like of Eliezer and his perspective, but I think suggesting he's just in this for the money is silly and unhelpful.
Then if it's not the case, and he argues the way he does, he's simply a hysterical idiot. It can't be any other way, since he's very wrong and ridiculously so on some of his takes on AI in particular.
The "Optimize Mac Storage" functionality you're referring to is not enabled by default.
You can manage settings for this and other storage optimization features in About this Mac -> Storage -> Manage, and System Preferences -> iCloud -> Option... (beside iCloud Drive).
Apple does not make this clear on their Sierra micro-site, and acts as if it either enables by default, or asks you with their typical confusing dialogs to enable it when low on space (which most users would get confused and click enable).
