I had this opinion too, but if you think about something like trading cards or any other “limited” collectibles that were mass produced, rather than one of a kind art, it’s sort of the same thing with regards to artificial scarcity.
You mean like Beanie Babies? "limited" collectible physical objects that went up and up in value.
Never heard of them? Yeah, that's because they stopped going up in value. Then stopped having value at all. It was about 20 years ago, who remembers that?
When Kellog's is making NFTs, it devalues the entire platform.
Trading cards aren't a fitting analogy, because only a few companies were/are in that business, and they each ran specific product lines. They're more similar to old lego sets in that sense.
NFTs are pogs.
The irony is that being digital, bits not atoms, make it easy to make copies.
Oh you invented digital scarcity?
Now you have 1000 copies of the "digital scarcity" business.
They're receipts showing that you "own" the card on display in the public square. And more than one receipt can be minted for that card. The most you can hope for is the earliest timestamp on the receipt.
For example, it wouldn't be hard for an artist to publish a video saying "Hey folks, this is my public key, and these are the NFTs for these pieces of art", and then publish that video in multiple forums like Twitter, YouTube, etc. Then if someone tried to come up with different NFTs for the same pieces of art, the NFT holder could just point to the video (and, as you say, if the artist was malicious and tried to dupe his own NFTs, the earlier one would win).
This kind of "identity validation" is all over the cryptography space already - that's basically how Keybase proofs work. Heck, lots of HN commenters put their proofs in their HN account signatures.
So then how do we know that artist actually created that art? For all we know, that artist took someone else's work and was just the first to mint NFTs for it on that particular chain. Maybe the legitimate artist minted NFTs on a different chain later so nobody will ever believe they created it because of the timestamp.
As I understand it, this sort of 'theft' is happening all the time right now.
Not just "an artist", anyone can. And they do. Many artists' works are being exploited in this way without their consent or even knowledge.