One of the questions asked ("Why do I have to give 200€ more to get the s24+ just to get these simple features?") was comparing S24 to S24+. While I have not looked it up, traditionally those versions range from SXY (small) to SXY+ (medium) and SXY Ultra (large), but are otherwise the same phone, so I would be surprised to hear if e.g. the S24 was foldable but the S24+ was not?
As for whether it gets more expensive to make something foldable vs. to make something more compact, I suspect the devil is in the details, so ymmv and you just kinda take each option as it comes. Other factors may help mitigate those costs e.g. a younger company trying to break into the big leagues might try to give phones away for virtually no profits in exchange for their increased market penetration (e.g. OnePlus used to be somewhat this way, now they are in the big leagues, more or less).
But your other point, about more materials: no, I believe that it's more complex than that b/c it's the effort of fitting things into tighter spaces that is more constraining. Imagine packing for a long vacation and/or a job interview at a far-away place and you get the idea - if you can fit everything into one suitcase that's good, but a tiny backpack is much harder to accomplish, and to take nothing and just live with what you can carry on your body alone is REALLY tough! (especially if you want all the normal features like not smelling bad) i.e. the materials costs, while not negligible, have not been the driving/limiting force for many years. At least according to everything that I have read, but I am no phone manufacturer!:-)
I am not sure if I ever want to own stock but... yeah I get what you mean. It was "ours", at one point. Then he made it clear that it is "his". Okay, lol, have fun with that. Spez, the canonical power-tripping Reddit mod.
I wonder what else he ruined too - like are people never going to wear Fedoras again, as a result? (although it was kinda on the way out regardless I suppose)
And btw, I am having fun - I must admit that I enjoy the Fediverse far more than I ever did Reddit. Lemmy is now to me what I imagine Reddit used to be, in its early days. I don't mean to be mean but... the people here are actually worth talking to.