It is playing on the psychology of the bidders. You want the bidders to be invested, to want to win the auction. To compete to win the prize.
Also, consider this: if the reserve is too high, and no one bids on it, then everyone looking at it is going to wonder what it is really worth. If there are several other bidders, then that gives reassurance to the rest for the price they each are bidding.
Also, consider this: if the reserve is too high, and no one bids on it, then everyone looking at it is going to wonder what it is really worth. If there are several other bidders, then that gives reassurance to the rest for the price they each are bidding.