It's the money/time factor for most gamers. Work more, earn more, but have less time to play. Work less, play more, but have less money to buy all the games worth playing, much less multiple pieces of hardware. If you find yourself scrutinizing every game purchase, you're probably not in the work more, earn more, less free time category, unless it's to scrutinize which games are worth your time rather than worrying about the cost.
If you have enough disposable income, and you are really into gaming, you'll probably have every piece of hardware that had a game (yes, even if it was just one game) you wanted to play or try out. And you'll probably end up picking up the other buzzworthy titles once you have the hardware as well.
There comes a certain point when you have enough money for the relatively inexpensive hobby of gaming that getting the maximum amount of entertainment for the dollar is not even an issue anymore.
Unfortunately for most people in this category, more important things like having a wife and kids start to demand most of your free time. Of course if you happen to find yourself with a gaming spouse or girlfriend, score one for you.
Typically at that point, it's simply a matter of having the time to play the games you inevitably start accumulating (including unopened, unplayed games). You play less to the point that your gaming habits are more in tune with the casual (in this case meaning occasional player) gamer even if you still buy games like a hardcore fanatic.
If you're a gamer with a lot of disposable income, there's no reason why you'd limit yourself to releases on one platform, especially not to save on entertainment costs if games are your favorite thing.