Because it's on eBay, and all sorts of scams, shills, and stupidity happens. Look at the bids and you'll see a 7 feedback member who seems to keep pushing up the amount a little at a time to sniff out just how far the existing bid can be pushed. Once they find it (by going over that real bidder's peak amount which makes the shill "winning" the listing with the maximum bid), they can retract their last bid and leave a real bidder at the limit of their bid.
Has nobody realized how often eBay's "rules" are skirted, and blatantly broken, every day? There's no eBay police patrolling each listing. Some of these sellers come from countries where there is no Consumer Advocate, no laws against scams, and it's considered good business to bilk a customer out of as much money as possible by hook or crook.
Hell, look at how many of YOU (meaning Omega Forum members) break PayPal rules EVERY TIME YOU SELL SOMETHING by requesting Friends & Family payment! Don't cast stones if you live in a glass house.