Most of the PC gaming market buys prebuilts and these pretty much exclusively offer Nvidia. I can see why someone not interested in DIY won't even consider looking for the unicorn Radeon build."Oh but consumers are deciding that Nvidia offers better value". We know this isn't true, and I really dont want to have to have the discussion where I have to demonstrate that consumers aren't all highly informed, rational people who are good at thinking for themselves like the alternative argument would demand be the case.
There are also plenty of rational reasons one would rather just buy Nvidia. AMD cards these days aren't even much cheaper than their Nvidia counterpart.