Anyways, I'm not even old yet, and I'll never be able to tell the difference between 1k and 4k video. Maybe on a Jumbotron screen at a sports stadium, but I don't go to those either. 10-bit color depth is merely a filesize efficiency gain over 8-bit, in exchange for a higher multitude of processing requirements.
Actually, you can tell. I'm using a 720p wall projector and my eyes can see the glaring difference between 1080p and 4K (both downscaled to 720p by the projector). Way to describe it, 1080p videos look like lossy JPEG compressed pictures, whereas 4K is closer to the lossless PNG picture format.