In sealed auctions, you want to win by bidding the most. But if you win by more than $1, you could have paid less.

In this version, you just bid to win and the seller lets you adjust down to that perfect "just barely winning" bid afterwards.

It turns out the seller makes more by everyone bidding to win than they lose by letting the winner adjust their bid after winning.

That's because the 2nd place bid ends up being higher than the winner's used to be.