I have prime for the no rush shipping. Every time I delay my same day or next day shipping to the 3-4 day no rush shipping I get a few dollars of digital credits which I use to buy ebooks. Over the course of a year it essentially pays for the cost of prime with free books I would have bought anyway.
I have never not been able to pirate a book, if you're interested. Book piracy is super super easy
I only support book piracy because most of that money goes to a publisher anyways, and Amazon gives credits because they take a huge cut anyways when people do pay out of pocket.
The hoops people jump through to justify why this way of getting free shit doesn't hurt anybody is nuts lol.
Trust me when I say music artists, writers, and anybody else selling their creative arts are getting most their money through direct sales. Having to justify your theft by saying you're stealing more from a nameless corp instead of the person who created it doesn't mean shit. You aren't Robin Hood.
You're hopefully just stealing from someone who won't notice because you're hopefully too poor and they're hopefully too rich.