In this market, OBO means: I think my game is worth "x", but some dumbass just bought another one for sale at a higher price than I listed mine, so I want to catch the new market price.
It's really the equivalent to the housing market and hoping to get 2-3 buyers who will bid against each other and present a windfall to the seller. I don't begrudge the sellers making money, it's just a bummer if you are a buyer.