There’s a lot of confusion here about why NFTs are valuable if the buyer doesn’t get to own the image copyright. This should not feel mysterious - NFTs are just like baseball cards. If you buy a Barry Bonds baseball card for $1,000, you don’t own the artistic rights to the image on the card. All you own is the card itself, which has negligible manufacturing cost. It would be trivial for any card company to produce a…
If not for the energy costs NFTs would be just like you describe above - a somewhat pointless but harmless hobby for enthusiasts (what good does speculating on baseball cards do in the world? What good does speculating on art do for that matter? As far as I can tell "little to none" for both of these). Unfortunately that's not the case.
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.