The way I look at it is that I can buy a print of a van Gogh for $10 but the real painting costs millions. The key difference there is that the real painting is real and the art house will some sort of provenance record that lists all previous owners all the way to the artist.

In the same way, when you buy an NFT you're buying the provenance without buying the actual art. The art is understood to be easy to reproduce, you can download it and print it yourself if you want to hang it up on a wall.