It's a Ponzi, and the value holds as long as the narrative behind NFTs also holds. Remove the possibilty of "easy money", do you believe the street artist would sell his work at inflated prices? I feel sorry for the last person who bought it at ATH with no willing buyer. Who would he/she feel losing his/her money? Scammed.
I could understand this market if people were actually buying NFTs because they wanted to collect them and keep them, so even if NFTs ended up being worthless at least they could have fulfilled their objective, but people are buying NFTs to resell them for a higher value, something that is incredibly difficult to do when the market is now filled with NFTs and their number does anything but grow, creating an even bigger supply when the demand is not growing a the same rate.