He's not bidding unopposed. You have to understand ebay's current "automatic bidding" system.
Say john sees the bottle and figures he'd pay up to $2000 for it, but no more. So he places his bid and enters the maximum he's willing to pay, which is $2000.
Let's say that the bottle has a minimum bid of $10. So john's bid is now entered at "$10", even though he's got a max of $2000 on it.
Now fred comes along, sees the $10 bid, and decides to bid $20 on it.
The automatic bidding kicks in, and outbids fred at $21. Then ken sees the auction and bids $100 on the bottle. The automatic bidding now outbids ken at $110. Then wilbur comes along and really wants the bottle bad, so he bids $5000 on it. The automatic bidding kicks in, and john's $2000 is finally outbid by $10.
At this point, the bidding history shows:
J**n $10
J**n $21
J**n $110
W**r $2010