The value is purely artistic. Which is its own value, to be fair. But people aren't buying these expensive cards to use them in the game. They just want them for the art (or simply the rarity)
I think its pretty much just entirely based on a current hype cycle, not even really art per se, I mean the cards aren't hand drawn or anything, they are mass produced cardboard.
Eventually the market will implode like the sneaker resale market did and people will move on to the next thing that gets hyped.
Underseat floatation devices are rarely used. Do they have no utility whatsoever, as was claimed upthread for all pokemom cards?
The spendy cards don't have utility to match their price, but the commons are fine. If it's correct that all of the spendy cards have cheap equivalents, that's great for everyone. Nobody has to feel like they need to spend big money to get a black lotus and hope they don't damage it in use.