I never claimed that IPFS magically ensures permanent storage, but the connection between the IPFS content ID (hash) and the content is permanent: If you have a

I never claimed that IPFS magically ensures permanent storage, but the connection between the IPFS content ID (hash) and the content is permanent: If you have a copy of an image or other data, and an NFT with an IPFS content ID, you can show that your file is the one associated with the NFT. That's true even if the entire IPFS network were to disappear since verifying that a file matches a content ID is something you can do locally without depending on IPFS. As to permanence, IPFS makes it easy to pin any available data on your own node to ensure it stays around. Even if it disappears from the network for a time it can be re-added with the same content ID as long as someone retains a copy. Just make sure you save it somewhere, preferably before spending money on the NFT. If the file completely disappears your NFT won't be worth much.