Why is NFT expensive?

I've been hearing a lot about NFTs and their skyrocketing prices, but I'm still puzzled. Why exactly are NFTs so expensive? Is it simply because of the hype surrounding them? Or is there something more substantial behind the high prices? I understand that they represent unique digital assets, but what exactly makes them so valuable? Is it the rarity of the artwork or the credibility of the artist? Or is it the potential for future appreciation? I'm really curious to know the reasons behind this phenomenon and how it fits into the larger cryptocurrency and finance ecosystem.