It isn't surprising. Any phone maker's sandwiching two smartphones together so it becomes 2x the price.
I'd never buy one because of durability concerns and it'll add another step for me to use it.
You're not sandwiching two phones together. It's just a bigger display. This isn't like fusing two m-chips together. You also seem to forget at this point, this type of device is over 6 years old. Is any other folding phone two phone fused together? Nope.