It's like claiming you own Facebook because you bought a link that redirects to it.

Wasn't it more like a receipt with an url on it that may or may not still be the image that was at that url when the purchase was made. Or maybe you could do a hash of an image, at which point changing a single pixel or cropping it would change it into an image you don't "own" and most people won't have any idea how to even check it.

Really, with the lack of tech savyness out there, the best way to own an NFT would be to just lie about buying one and what it is.