Its called investment. Sony put money into PS3, with hopes that Ps3 sales will eventually break even and potentially create profit. They are currently losing apprx $18 per console, so the break even point is coming pretty soon.
Since PS3 is already using the 'next gen' format, its life-cycle is going to be pretty long- much longer than Xbox and wii. Also unless, Xbox or wii is going to skip a data format generation (or they make their own?), they'll be licencing blu-ray from sony, which means every Xbox720 or wii2 sold, part of that sale will go into Sony's pocket.
Sony will tie for 2nd this generation but they are in much better position to win the next one assuming we're still heading for the bigger resolution and graphics trend.







