People who buy closed beta keys are NOT dumb. BF: BC2 Closed Beta, StarCraft II Closed Beta, WoW: Cataclysm Closed Beta, CSGO Closed beta, DotA 2 Closed Beta, Diablo III Closed Beta, etc.
They know what the final product will cost ($50-$60 / €50-€60) and even then they want to play BEFORE anyone else. OK, if you they want before anyone else, they have to pay up to x20 times the RRP price. So easy to understand.