I did a bunch of research on resolution when 4k started being a thing. I was curious how it relevant it was when compared to the capabilities of the human eye. I was expecting to end my curiosity with a yes or no answer. Hours later with dozens of articles and scientific papers under my belt, I came to the conclusion "maybe?".
The problem with 4k and 8k is that they might be better than what you can physically see with your eyes. If you are looking at a 27" monitor that is a couple feet from your face, you can likely see the difference between 1k and 4k. Unless you have uncommonly spectacular eyesight though, you probably won't be able to see the difference between 4k and 8k. The answer isn't so simple though. Being able to see the differences between the super high resolutions is a factor of screen size and how far away it is from your face. Depending on the circumstances, you may only be able to discern improvements up to 1080p.
The main reason I dove down this rabbit hole of research, was to decide if I wanted to try for 4k on my gaming rig. At the end, my decision was an easy one. No. It wasn't worth it. While I was doing my research though, I came across several other factors that make much more of an impact on your visual gaming experience. That is the refresh rates, response times, and pixel pitch. Those are much more of a factor than the resolution. This is particularly a problem when, for instance, your computer can crank out 100+fps but your monitor only has a 60hz refresh rate.
Then there is the practical application of 4 and 8k. Our data infrastructure can barely keep up with streaming 720p reliably. Netflix accounts for over 1/3 of all internet traffic (36.5% in 2015). We don't have the bandwidth for what our TV's can do. Streaming 8K would either clog the internet or leave us waiting on a loading symbol.
For us though, it's all about the gaming application. It's even worse there. Most people's computers can barely handle 4K and it's situational at that. If you are in a combative game, most gamers wouldn't dream of running around with the settings cranked that high. They turn it down to guarantee the more important factors to combat, frames per second and lag.
So long story short, 8K is pretty. It really does look amazing if you look closely. The problem is, we're just not ready to put it to work for the every day stuff. At least that's my take on it.