Exact same argument for crypto though. It is all just supply demand. BTC has much more demand currently and likely more sustainably. Alt coins are just less popular. It is all just supply vs demand.
NFTs use the same machinery but the premise is that you own something else, e.g. an image (or real estate!) but nothing on-chain actually grants that ownership. To the extent real ownership exists at all, it lives entirely off-chain, e.g. in a legal contract (that would hold with or without the blockchain).
I am not a fan of crypto either way but NFTs are just ridiculous.