I remembered when i got my first 1440p panel, i was like "holy crap it looks so 3D!"
Then I got my first 4K panel, it was the same feeling too! only well.... less so in a way.
Something tells me the more you increase the resolution, the apparent difference isn't as dramatic as it used to be.
going from 1080p to 1440p was like but from 1440p to 4k was like
I think the only way i'm going to tell is staring at the horizons in the background to tell that, yes, I can...