Your reasoning is flawed. iPhone 14 fits the same use case as iPhone 11, but Foldable fits a different use case than normal phones. You may find Foldable useless but that doesn’t make your reasoning any less flawed.
Someone who wants a phone and a tablet, but doesn't want two devices, and doesn't want to have to lug around a tablet that doesn't fit in their pocket.
If it wasn't so expensive, and I wasn't still skeptical of the durability of the folding tech, I would buy this. I don't have a tablet for the above reason, but would absolutely make use of something like this.
