This has been a curious question of my own so I have done some looking of my own into this subject. From what I could find, it isn't truly worth it for gaming. The average person sits 1-3 ft away from their monitor. At this distance, you would need a 30+inch monitor to see any difference between 1440p and 4k. Unless you plan on gaming on a large TV, there is really no point in spending the money on parts for 4k gaming.
Also, the high-motion scenes involved with gaming in general reduce the effect of resolution on qualityy. When you are in a very fast moving scene, you are much less likely to notice any blur caused by a lower resolution because their is already motion blur. At his point, 4k gaming is not truly worth the cost unless you just have money to spend and you feel like getting it. The true purpose of 4k is for high end video and photo editors, as well as big screen TV's and home theaters.