I bought a pro before I had a 4k tv because it made an online game I play a lot run better. I have a 4k TV, but I'm buying into PS5 for exclusive and better running games, not because of marginally better graphics.
Sticking to my PS4 won't let me play the new ratchet and clank for example. And once we get beyond the launch window less and less games will appear on both systems. This is also why I don't give a stuff that on paper the Xbox CPU is marginally faster than the PS5 one. It's all about the games, but that's just me.
If I really cared about FPS or 4k I would play more games on my PC and not buy either console - but I prefer sitting on my recliner sofa than at my desk