Book sellers are rarely stuck with unsold inventory. They almost always have the ability to send unsold inventory (though not magazines) back to the publisher for full credit.
To remainder paperbacks, instead of sending the entire book back for credit they'd rip off the covers, send those instead, and dumpster the book. I don't know if they do this anymore. When I grew up in the 80s, I read an enormous number of coverless books:)
So then if you have sufficient capital, you park it into your own book for a few weeks and then return it all later once the best-selling status is achieved?
I can't imagine publishers would let this happen more than once or twice before revoking this ability for the seller. Inventory handling is expensive.