Caporegime
I know people don't want to hear it but Nvidias mindshare is so strong that for AMD to make serious market they have to offer 30% more performance per dollar to make people switch. That could come in two forms: Either you launch an AMD GPU with the same performance as Nvidia but it's priced 30% lower OR you launch at the same price but it's 30% more performance
The reason rdna3 isn't doing much to hurt Nvidia is because so far AMD has chosen to launch at the same performance tier at Nvidia and only price it 10% cheaper when they need to price it 30% cheaper or offer more performance
£400 where Nvidia sell at £600, the amount of market share AMD would have to take from Nvidia for that to make sense is never going to happen, the margins on that would be almost none existent.