You jest, but that might reflect the attitude of "punishment bidders" in some of these auctions. I think some people put in high bids thinking, "If I don't walk away with this book, at least I'll make somebody else pay a stratospheric price for it."
I think that some shill bidders have it down to a science; they watch to see how long the other bidder hesitates before entering another bid, and when it looks like the other bidder is slowing down, they stop bidding. Their goal is to be the underbidder. Some of them are good enough at it that they rarely get burned, but they probably set up bogus accounts so that they can default on the payment without consequences when they do get burned badly.