NFTs are disappearing left and right because they're stored on transient or entirely centralized data storage such as IPFS or AWS.
Before you buy an NFT: make sure it's stored on a Permanent data storage protocol, otherwise it could disappear.
Currently, the only Permanent data storage protocol in production is: Arweave.
To see examples of lost NFTs and learn more about how to keep your NFT, click "learn more".
We hate spam, and we don't use third party servers to store info.
What: NFTs stored on IPFS are
Why: IPFS node operators have zero incentive to retain files. As more files are uploaded to IPFS, the servers automatically delete old files to make space.
When: Many IPFS assets on Niftygateway are gone, including those uploaded by popular artists 3LAU, Grimes, and Deadmau5. The only remaining image data for these NFTs is on the Niftygateway web server, which is not decentralized, not a blockchain, and not permanent. The result is the equivalent of owning the deed to house which is on fire.
For example, here's a link to what should be a 3LAU NFT image on IPFS as seen by querying the relevant smart contract here. Read more on Decrypt
How: Protect yourself. Use checkmyNFT.com to make sure the NFT data is on Arweave before buying an NFT.
Developers: Protect your users by uploading NFT data to Arweave. For the best information regarding integration, see here and then join the Arweave Developers Discord channel], where you'll be greeted by a wonderful global community of friendly developers who are happy to answer any questions you have around the clock.
Now go forth and practice safe NFTex. Even more detail here: https://arweave.medium.com/permanent-nft-storage-on-the-arweave-network-41f38d700a2d