Feel free to quote this and laugh at me but by this time next year I doubt this will be a topic
The latest updates for anyone interested: https://blog.ethereum.org/2021/09/28/finalized-no-29/
Every estimate so far has been wrong.
NFTs themselves don't have any energy costs. Depending on what network you're using for buying/minting/trading NFTs, there might be energy cost associated with it, but not all NFTs are equal. NFTs based on Proof-of-Stake networks won't have the same energy cost as NFTs based on Proof-of-Work networks.
Unfortunately, it seems that most NFTs are based on the Ethereum platform, which is currently Proof-of-Work. Fortunately, Ethereum is moving to Proof-of-Stake slowly but surely.
But the point still stands, NFTs themselves have no energy costs, only the transactions on the network where they live have that.
The sunk costs of obtaining something rare or difficult to get (like titanium) is a factor only for the next person who desires titanium.
Since there is no cost to see or copy a jpg, there is no "extra value" added in an NFT. Not even energy costs. The end product still has zero value.
A simple corrolary is wine. Swill stored expensively doesn't acquire new use values from the storage. The expense of storage doesn't accumulate to the value of the NFT. Whereas the expense of obtaining real goods like metals is exactly what sets their value.
Unfortunately that's not the case.