i am a pirate and i extensively use a borrowed overdrive. i still buy kindle from olx because i can get them on the cheap, much more than amazon itself.
Also, when I buy physical books, I often buy used ones. At local used book stores, I can often get them for $5 or less.
1. You won't see those discounts in certain categories (e.g. full length Stephen King novels). Whereas with physical books, you can expect to find cheap used ones no matter the author (unless it's a rare book or something).
2. You have to time purchases to the discount availability. With used physical books - as long as the book is popular enough - you can get that discount at any time.
As for physical books, I'm trying to get rid of 200 or so I bought pre ebooks and damn it's a pain.
Do you know what stores offer that? Last time I looked around it was mostly small shops with very minimal book offerings.
ebooks.com but you have to look if the book you like has an unencrypted epub versions
smashwords.com
This isn't strictly true since you can also read Amazon ebooks on 3rd party android devices that have the Kindle application installed.
It's true in the more general sense that the Amazon ebooks have DRM that limit interoperability.