At that point its better just to get a customized desktop. For the price you can get a desktop thats loaded with much more, or pay less and get the same specs.
And yes, there are alot of hardcore gamers out there. In fact, there are so many, they are one of the primary things that drive the high end pc market. They wouldnt push to make a computer like that unless they knew alot of people would buy it. I wouldnt bet much against the the fact that were it not for gamers, high end computers would not be nearly as far along as we have come.