It very often does, and it is certainly the case for most high-value NFTs. It is indeed not the case if you create your NFT on OpenSea and do not take the additional step of freezing the metadata.
Also, there are many artworks that change, so a hash to a single file is not necessarily the right solution.
In those cases does the blockchain still have the URL as well? And you might end up with a collection of bits that matched the hash in the blockchain but was no longer at the original URL? What's the next step then?
(The "artwork may change" bit seems like it becomes even more weird and potentially nightmarish edge-case/potentially-losing-your-purchase-wise.)
If you purchase one that’s worth say >4 figures then, yes, yes you should! Also at that point, you’re either part of the 1% or at the very least owe some due diligence to your investments.
In reality, the internet is a big copy machine and you’re probably safe. But you should still back it up.
Sounds like it has the same value as saying "I used to own this one famous painting before it burned down in a fire."
A hash corresponding to the bits in your file? Sure, that works, you can say "yep, this is the image, I own it." A URL plus a hash + the bits. Sure, that makes sense, even if the URL goes away, you can prove that those particular bits belong to you. A URL that's now dead and nothing else? Nah.
You can say that this is a stupid game and people shouldn't be playing it. I didn't make it up and I don't take part in it. I'm just trying to tell you what they're doing
IPFS is basically Bittorrent plus a financing system. Arweave charges US$5/gigabyte for permanent storage on IPFS. This is supposed to be forever, funded by investing the money and speculating in the declining future price of storage.
You can supposedly put academic papers on Arweave's version of IPFS.[1] But if you try "Browse", nothing appears. This acts like another one of those distributed systems that isn't.
[1] https://ss6puabcq3ch.arweave.net/5Yeg3wT4COQL6Bz-tdp9xlmeiwg...
That doesn't match my definition of IPFS at all which is simply "P2P immutable content hosting". How is it a "financing system"?
https://arweave.medium.com/arweave-announces-new-funding-fro...
There is no mechanism on the Blockchain preventing someone else creating a new NFT with the exact same hash.
But to truly _own_ something, all the cryptographic guarantees in the world won't change the fact that true ownership can only be enforced through violence. And if your private key can be stolen by hackers in countries without extradition treaties, one could argue that anything digital is only "owned" in the absolute weakest sense of the word: no one has tried disputing it yet.
What's to prevent another NFT from pointing to the same data and copying the hash?
But on the blockchain itself, the NFT is just a smart contract (bit of code, bit of data) that knows it's current owner, it's name and a URI pointing at the image. There zero mechanism preventing duplicates.
Hell, it's such an unregulated market that the NFT might be based on a custom smart contract with a backdoor that allows the creator to steal it back at any time.
e.g. the EtherFreakers contract is immutable and contains a git commit hash (line 83: https://etherscan.io/address/0x3a275655586a049fe860be867d10c...), so you can prove you have the code which generates your freaker.
Yes, you can run your own Etherium node and server, and connect a MetaMask wallet to it.[1] As Moxie points out, nobody wants to do that.
Worse, the blockchain does not, apparently, contain the hash of the data. You can't even prove you even have access rights to the data if the hosting service goes down. All you own is a link to a URL.
There are more Ethereum full nodes than two, but how many will accept web queries? That's a service.
[1] https://media.consensys.net/how-to-install-and-synchronize-y...