I wouldn't personally buy an NFT for those purposes, but tons of NFT owners buy them to be able to use them as profile pictures. Yes, you can put any arbitrary JPEG as your pfp including an NFT owned by someone else, but it'd feel the same as wearing replicas of branded clothing (and people mostly just don't).

That might not seem as meaningful as hanging them in your house, but I've watched it become that meaningful for a ton of people (as "irrational" as I think both NFTs and Hallmark cards are).