I don't think anything costs less when making a graphics card today than it did compared to two years ago at the Ampere launch. Have GDDR6 prices gone down? Substrate, PMIC, resistor, capacitor, PCB, VRM, shipping, etc. prices have all gone up. Best case, if everything else stays the same and Nvidia goes from paying $100 per GPU chip to $200 per chip, I'd expect that to result in a final product that costs $200 extra compared to the previous generation. Add in everything else and it's not really surprising to see Nvidia trying to get $900+ for the 4080 series. Sure, prices could be lower, but unless Nvidia has so many Ada GPUs that it doesn't sell out at launch, there's no reason for it to actually be lower just yet.
Now when RDNA 3 comes out, we'll see if Nvidia reacts with price cuts and maybe an RTX 4070.
I strongly doubt those prices. I suspect it's more like $8K per 4N wafer at a minimum (which was customized for Nvidia's needs and that increases pricing), and a maximum that might be twice that. 24GB of GDDR6X is probably $6 per 2GB chip, minimum, which would mean at least $72 for memory, could be more. Card and cooler and fans, probably $75–$150, depending on the model. Now add in all the PMICs, VRMs, capacitors, resistors, and any other surface mounted devices and I think a rough estimate of $50–$100 for all of those isn't out of the question.
So based on my estimates, it would be more like $300 as an absolute minimum (reality is probably somewhat close to $300 for a card like the RTX 4080 12GB), but a maximum would be more like double that, maybe more. Yeah, that's still $600 in base costs selling for $1600, but as Spongie points out, R&D and a lot of other things come into play, and this is the halo card for now. It was never going to be affordable.