Earlier quoted context omitted.
> You should put in a bid where you're exactly neutral between buying-vs-not-buying. Otherwise, you're leaving money on the table. This is asking people to make purchasing decisions whose outcomes will leave them explicitly not happy - a state of mind that every person hates putting themselves in. It seems that this is a problem the Vickrey auction solves. By charging the price offered by the 11th highest bidder, the…
> so actually the 11th will feel slightly miffed that they weren't able to purchase at that price. Why not including the 11th in the winners? That would solve the "unhappiness" of the 11th bidder; am I missing something?
So it's not really "why not include the 11th in the winner," it's "why charge the 11th bid and not the 10th?" I think the reason is that everyone feels like they have a good chance of it going for less than they bid (and so they feel happy), but it probably also incentives higher bids.