Sure there is. Anytime someone says "NFT", they are almost certainly referring to an ERC-721/777[1] token on Ethereum. What other blockchains support NFTs and have any kind of use?
Re legitimacy: how do you prove that any piece of artwork for sale in the real world is legit (the seller isn't violating someone's copyright or selling something stolen)? With an NFT at least, there's no such thing as a fake bored ape; the contract address that defined those is known. You can copy the image, you can even mint it, but it will be a trivially differentiable from the original, since it will belong to a different contract.
Re legitimacy: how do you prove that any piece of artwork for sale in the real world is legit (the seller isn't violating someone's copyright or selling something stolen)? With an NFT at least, there's no such thing as a fake bored ape; the contract address that defined those is known. You can copy the image, you can even mint it, but it will be a trivially differentiable from the original, since it will belong to a different contract.
Valuation is irrelevant to this discussion.
[1]: https://ethereum.org/en/developers/docs/standards/tokens/erc...