Do I really even need to upgrade my card? I like to play in HD but I don't have one of the 2k monitors or anything. I seem to get 60+ FPS in games such as ARMA 3, BF4, and DayZ Standalone. I always love to have the best performance I'm just unsure if it's even worth doing.
No, you don not. A 770 will play 1080p very welll and should be good for some time. You can always sli later on down the road.