Like a lot of the other comments it really does depend on what you are watching but would also mention it will also depend on your setup also and do you feel the need to upgrade.
Myself I’m perfectly fine with bluray or dvd and not so long back I purchased a bluray player that upscales to 4k (it doesn’t play 4k discs but upscales the bluray to 4k) either way Terminator has never looked better on my 12" portable b&w😂, all jokes aside my tv is 56" 4K and the picture on dvd is just as good compared to bluray to my tired old eyes.