Depends on how good your eyesight is. Nearly a decade ago I saw an 8K monitor in person and it had a very noticeable “wow” factor above 4K. Now? I probably wouldn’t be able to see much difference.
I keep telling the missus that we only have about a decade remaining when it is worthwhile to invest in a top-tier television. After that, even with glasses we won't appreciate the upgrade enough to be worthwhile.
Ditto with PC monitors. I spent a lot of money on 4K as an early adopter because I had better than 20:20 vision and could appreciate the difference. These days I sometimes don't even notice if something is running at 1080p! An upgrade to 8K would be a waste of money.
Of course, when my kid grows up and I have to buy him new electronics, I get an excuse to spend money on expensive gadgets again...