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 he proceeds to monopolize the shelves as he roots through all the books and searches them manually on his phone (which I assume it internet-enabled).
I can't help but get a little annoyed by his presence, especially once I figured out what he was doing. He wasn't reading all those books, of course; he was hoping to make a profit on them. I, like many others, look for books to, you know, actually read, and I view this man's actions as rude. Likewise, when I offload a box or two of books to this same store, I am doing so out of a desire to give back to the local community, and it kind of chaps my hide that this asshat with his phone might buy one of my tech-related softbacks for $1 and sell it on Amazon for $5 or more, potentially denying some poor, local kid who may want to better himself by stumbling on that same book I donated.
These days, because of this leech at the thrift store, I'm more inclined to simply shred my books (they make good animal bedding and compost well) than take the effort to load them up into the car and donate them. Sure, that may be viewed as somewhat selfish, but then again, that's exactly how I view that guy who buys all the books to make a quick buck.
Shredding your books is not doing anyone any good.
I agree that there is a temptation to wonder 'what if' about some young starry-eyed dreamer who may stumble upon a book who has instead had that chance snatched from him and will now turn to a life of crime but the reality is the book is far more likely headed for the trash heap than to a loving home. That being the case, it is far preferable to have the book go to a reseller and on to someone who wants it.
On the other hand, the copy bought on Amazon for five bucks might wind up in the hands of some poor nonlocal kid who betters himself using this book he really wanted.
I have a bunch of books I bought at garage sales which I never really wanted but picked up because they were cheap (like, one-dollar hardcover biology textbooks) and I thought I might look at them someday. The world would probably be a better place if they had been bought by someone who really wanted them... or alternatively by a middleman who could sell them on.
Of course I could sell them myself, but it's not worth figuring out how to do so in order to make whatever small amount of money is involved.
I've also donated a lot of used technical books to thrift stores and library sales, and if they're picked up and re-sold by guys like this that's fine by me.
Another alternative would be to sell your books on Amazon yourself, at the going rate, and then donate the proceeds to a library or other organization that has local impact.
This is easy to solve. Just start selling your book for $1 on Amazon.
If nobody else has it on amazon, this guy isn't buying it and putting it up there.
Your stated benefit doesn't exist.