I'd say that there's a strong expectation amongst most people that something described as 'art' will increase in value. Anyway, the first duct-tape-banana will definitely never go off, because the silly sod ate it. (He was a performance artist, and he called the act of eating the banana 'Hungry Artist'... makes me want to weep.)honestly,anyone that is buying a banana taped to a wall is even more stupid than a NFTer: at least NFTers are being told their thing will be worth something in a few years while the taped banana will go bad in a couple of weeks tops. either way there are lot's of ways to be stupid and both taped banana buyers and NFTers are just two of the many out there.
If you look at some of the NFTs being sold though, it's equally hard to imagine why anyone would think they will increase in value, especially since many people don't even understand Blockchain. They've just seen what happened with Bitcoin and think it might happen again.