They have some value relative to the system they are found in. Consider some fungible tokens which still have value. Say gold coins in online video games. These have some value, even when trading them is against ToS and will get you banned. Their value is relative to their usefulness in the game, and as long as the game in enjoyable, people will assign them so value relative to the enjoyment they can extract. Nothing about the game must be engaged in. There are people who live their entire lives without ever touching an MMO, much less a specific one like WoW or Runescape. Yet fungible tokens still have some value within those ecosystems.
Mobile games have taken this much further, with people buying fungible tokens for hundreds of dollars for the enjoyment they get, though this has become questionable as more of the game is engineered towards feeding an addiction which will cause players to pay more for their enjoyment.
The issue is the approximate cap on this value. Even by the inflated standards of whales paying for mobile games, we still see a cap of value around $1,000s for a month of value. Thus an NFT that provides value in a similar ecosystem should be able to max out at a similar evaluation, assuming it is tied to a system with as much investment in the fun as the big hit mobile games (which is often quite a lot of investment compared to what any single player, even whale, is spending).
We see NFTs going for much more than that in systems that have far less investment in being enjoyable, which I think can be contributed to people investing to get rich by selling at an even higher price.
In conclusion, I think that NFTs can have some inherent value, as much as fungible tokens in a game can, but that such value would be far below where the market currently is. Someone should only spend as much on NFTs when the enjoyment they get from spending on NFTs matches the enjoyment that similar amounts of money would bring from their other hobbies.