  In a second-price auction with i.i.d. (independent identically distributed)
bidder valuations, adding bidders increases expected buyer surplus if the
distribution of valuations has a sufficiently heavy right tail. While this does
not imply that a bidder in an auction should prefer for more bidders to join
the auction, it does imply that a bidder should prefer it in exchange for the
bidder being allowed to participate in more auctions. Also, for a heavy-tailed
valuation distribution, marginal expected seller revenue per added bidder
remains strong even when there are already many bidders.
