Most of the comments assume that with NFTs you are buying just a piece of digital image with no utility whatsoever. And yes, it is the case with most of the things we see on https://opensea.io/.

But on the other hand, there are a bunch of interesting projects out there where you can do some cool things with your NFTs, like the "card game" Axie Infinity and other ripoff projects - with a very few original ones - inspired by it.

NFTs for collectible card games is promising and maybe this can lead to some other interesting use cases in the future.

Anyway, I recommend searching for "utility nft projects". Most of them seem just like something to steal money from other people, but again... there are some interesting things coming out from it.