I find that it really depends on the content on the size of the display.
The larger the display, the more you'd benefit from having a higher resolution.
For instance, a good quality 1080p stream vs a highly compressed 4k stream probably won't look much different. But a "raw" 4k stream looks incredible... think of the demos you see in stores showing off 4k TVs... that quality is noticeable.
Put the same content on a 50"+ screen, and you'll see the difference.
When I had Netflix, watching in 4k was great, but to me, having HDR is "better".
On a computer monitor, there's a case for high-resolution displays because they allow you to fit more on the screen without making the content look blurry. But on a TV, 4k + HDR is pretty much peak viewing for most people.
That's not to say that if you create content, 8k is useless. It can be really handy when cropping or re-framing if needed, assuming the desired output is less than 8k.