Because they put money on the game??

I'm not surprised, but still sad to see the immaturity in the replies in this thread so far.

Why am I interested in the sales? Because besides playing games, I'm also interested to see in what direction the future of the gaming industry is heading. And with this I don't mean "Sony wins this or Nintendo outsells that". I mean that it's interesting to analyze and philosophize(sp?) about what kind of ideas, concepts and games stick and change the course of the future. Who could have thought back in '98 that shooters on consoles would become so big? Well, if everybody disregarded the business side of the gaming nobody would (just to name an example).

lol i only predicted the first week or second week. 

But the vg sales chart isn't accurate a lot of the times, so people are fighting for no damn reason

It is mostly for bragging rights, so that you can win a console war

If you're a fan of something and it doesn't sell well. Chances are that you won't be getting more of it.

I'm still waiting on my Mirror's Edge sequal. I bet I wouldn't be waiting if the first had sold a million on day one.

Edit: As for why should people care about it selling more then the competitor. There's probably less of a good reason unless you're worried about the console you support copying some successful but undesirable traits from the competitor (For example, I'd hate the idea of Sony saying "hey getting people to pay to play online seems to work ok for Microsoft").

sell the most console systems, sell the most console system, sell the most console systems in the world!

I wish I knew.

I'm not sure.

noooooooooo noble. users are interested, and others troll PS sales which brings out the defensive nature of PS fans who own multiple consoles.