You can pick up a 24" 4k monitor that has 458ppi. Few people have video cards capable of displaying 8k. Gamers care more about high fps over higher resolution. Few people sit close enough to their monitors that they can even perceive a difference between 100ppi and 1kppi.
If you use Windows, running at something other than 100% DPI scaling can still be problematic with some apps. I've got a 17-inch laptop with a 4K display, but I actually prefer running at 2560x1440 100% scaling instead of 4K with 150% scaling. I think a 43-inch 4K desktop monitor would be just about perfect for my needs. 4K 28-inch (what I currently use) tends to be too pixel dense and so I end up setting Chrome to 150% scaling on a lot of sites. Once you get pixels down to a certain size, making the pixels even smaller doesn't really matter much for the user experience, but it can up the hardware requirements.