I think they thought that the item will be available and exclusive for them as the buyers. As I can see is that this brand of shoes isn't in the market yet and it is only sold in this auction.
That still doesnt make any sense. They pay money just for getting an unique item that only one persons own,but for what? The only explanation is because they want to seem cool in front of their friend, but still why would you be that stupid to pay for something virtual when you can use those money to buy shoes in real world and use them while also everyone could see them.