I think the use of the term "win" is to make the buyer feel good about his or her purchase.
You certainly are right that emotions often cause people to pay more for an item but to say that it is more than its "worth" is a subjective term.
The "worth" or value of anything at any time is what a willing buyer is willing to pay a willing seller in an arm's length transaction.
Values fluctuate (look at the stock market). When you buy an item you may be able to re-sell it for more or less.
So to draw the conclusion that one always overpays at an auction is erroneous. The value of the item is still ultimately determined by who is present and how badly they want it - and they then set the market price at that moment in time.
Thanks to AS I have bought many brand new items for less than I could elsewhere. From that however I don't draw the conclusion that everything at Best Buy is overpriced (although much of it is). If Best Buy is able to sell a product at the price they set, by definition that is the market value.