Why would you buy a 4090 ahead of getting the VR headset? If you want to get into VR, get the VR headset. Then if you find your 3090 really cant cope... get the 4090?
Just seems bizarre to me to be buying a GPU at £2k, for something you havent started doing yet? The VR headsets aren't cheap... why not spend this cash on those?
I get the people who are so flush with cash, buying a 4090 isnt really an issue as the 'value for money' part isnt relevant.
But actually saving up to buy one? Seems crazy to me. Surely there are much better things to buy that improve your gaming experience for that money?
New Monitor / Speakers / Keyboard / Mouse / Desk / Chair or how about a boat load of games?
Once the 4090 is in, and you have run your benchmarks and got yourself on TROH, you still have the same games to play as before. While its always exciting getting a new bit of tech, at this price the maths are hard to make work imo if you are saving up for it. That £2k saved could bring you far more smiles in other ways Id argue...