Earlier quoted context omitted.
It's actually of benefit - there is a book out there that I want but it's hidden in a library or garage sale in a city 1000mi away. This guy makes it available for me to buy at a price I set on Amazon - rather than the book ending up in the trash and me not having what I want.
Depends on perspective, I suppose. It can be a detriment to the local market. I frequent a local thrift store (Deseret Industries, run by the LDS church), where I always quickly scan all 6 book shelves. Every morning (that I've been there that early), there's one dude that rushes his way to the "new" book shelves (the ones that were just rolled out of the back and not yet sorted onto the shelves), towing a cart, and…
This is easy to solve. Just start selling your book for $1 on Amazon.