Two thing's I would like to point out
Selling large quantities of a product brings you savings for buying components in bluk and the like
Sony also expected to be making more money(less loss) on each PS3 because
They could not anticipate the financial crisis, and the consequent weakening of the dollar/euro against the yen
They did not anticipate the Wii60 stealing exclusives and dlc, which has lowered the attach rate of the PS3