But what is the point? Is there better gear out there then a full zunimassa? Are there like super legendaries? Like why care about your build when you have all the best stuff? You are essentially done... What is the point of finding new gear?
I'm going to try and break this down as simply as I can without writing a wall of text because it is very easy to do that when talking about this subject. In the most simple terms possible you are either playing this game for the rush of getting better gear or you are playing the game because you like the game and want to push it as hard as you can. Every guide you will see written is written from the perspective of someone in the second group. What that means is that gear is simply a means to end, it is just a hurdle that people have to jump to get into the best parts of the game.
Your question is what is the point? And the answer to that for the high end players right now is the Greater Rift system. They are timed dungeons that scale infinitely in difficulty. If you beat the timer in one dungeon you can move on to a harder one, then a harder, then even more harder until you simply can't beat the timer anymore (and it's worth noting the difficulty of these is WAY higher than the difficulty you can select from the main menu. Torment 6 which is the highest difficulty right now is equal to Greater Rift level 25 but people doing Greater Rifts are up to level 60+)
You kinda just have to figure it out for yourself. Do you like the game enough to try and push it to its upper limits or do you just want to get better gear? If you are only interested in getting better gear you will hit an eventual wall in the game where you are out of content as there is not always better gear to obtain.