All the above explanations are bullshit...

"Sellers" exist for one primary reason only: it takes an insane amount of capital to design and produce custum BTC mining ASIC chips + create the hardware and software necessary to hash with these specialized ASIC chips. Early to mid last year there were no VCs with balls big enuff to invest in ASIC mining therefore we have "sellers" like Avalon and BFL who really just intiatiated pre-ordering as a means to raise the necessary capital...

Even ASICMINER/Bitfountian had to IPO shares in theyre company to raise captital and the only reasons they even decided to sell some of there first gen Blades is because they have a responsibility to shareholders/must pay dividends + raise additional capital for research and development of the next generatin ASIC hardware they plan to implement...