I've yet to install an AAA game I can't play at very good settings, if not max, on my boot camp partition at 2560x1440 resolution. Mac Pro from 2009, here. I'll admit, I don't play everything, but I don't want to play everything either. It's possible there's some games that won't run well on my machine. I have no earthly idea what those games would be since I buy several AAA titles every year and those run great, but they may be out there. A more modern Mac would take care of that problem if it should exist.
The fact is, for all the bravado of a few PC gamers, game developers know that not everyone has a top of the line PC, so there aren't any games that require top of the line PCs. If game developers made their games only playable with the very latest hardware, they wouldn't be able to sell enough games to offset their development costs, much less marketing budgets. It makes no financial sense to make a game that a few thousand people in the entire world can play at max settings. They look at the average hardware configuration, and then they develop for that. People with higher specs get higher FPS but the exact same game experience since the human eye can't tell the difference. Let's face it, most of the developers are actually developing with consoles in mind, which people definitely don't upgrade every year because they can't. With a new console generation coming out (XBone and PS4), PC games will take another leap in requirements for a while, but then it'll all slow down again and rely more and more on new software features running on the same (roughly) baseline hardware.
I know some very hardcore gamers, who build their own PCs, play competitively, the whole deal. None of them upgrade their hardware every year. They play games just fine, and still brag about their frame rates years after their hardware came out. They upgrade their GPUs when and if it ever becomes necessary, which isn't that often. They tend to care about how fast their hard drive is for loading much more than the CPU. They only upgrade their motherboards (and with it CPU) when a new GPU comes out that requires it, and only if they actually need a new GPU (or two).
There are plenty of hobbyists who enjoy building very powerful gaming rigs, but those are hobbyists, and hardware is their hobby not gaming. Gamers care more about gaming skill and winning than than the specs of their machine. Specs do matter, but when game devs aren't targeting hobbyist systems, they don't matter as much to gamers as some of you are trying to imply. Real gamers know that 80 FPS and 60 FPS are indistinguishable, and they'll save their money to buy more games instead of buying faster hardware to get higher benchmark scores. They care more about their score in the game.
So by all means, build your own super gaming PC. It'll be overkill for just about every game that comes out for several years, but you'll have fantastic benchmarks to measure against other e-peens. If you just want to game, get a mid-to-high end gaming PC and cut corners on the rest of the hardware, it'll do exactly what you want it to for years to come. If you also want to do general computing, get a high end Mac with a windows partition and it will be comparably excellent performance in games under Boot Camp and serve you well the rest of the time in OS X. You won't have as big an e-peen going the latter two routes, but you will have a good gaming experience.
