You know computers have the ability to compress videos, right?

>Do I really need 4k HDR to enjoy Seinfeld?

No, but the difference between 480p and even 1080p is pretty significant and definitely makes the viewing experience just generally more enjoyable. But that's just Seinfeld, where you can basically close your eyes and guess what is being shown 90% of the time with great accuracy. Where this doesn't work is with movies/shows/etc. where the visual component is important. If you go to a LotR watch party and bring a 480p rip and expect people to watch that, then you might need to get your eyes checked.