My take on hard drive economics is that the cost of an HDD is relatively constant, modulo the platter count, while capacity increases over time, as the components are pretty much the same in each generation.
There's one exception to this - HAMR added additional components, and a corresponding increase in BOM cost, but there's probably a learning curve on this.
However the recent AI data center boom is probably hitting HDDs in two ways - (a) general demand for anything datacenter-related, and (b) high DRAM prices, with most HDDs containing 256-512MB of DDR3. (I haven't physically examined the newest drives - they may be DDR4 and go beyond 512MB; also the 40TB supposedly includes NAND flash, adding yet more cost)
There's one exception to this - HAMR added additional components, and a corresponding increase in BOM cost, but there's probably a learning curve on this.
However the recent AI data center boom is probably hitting HDDs in two ways - (a) general demand for anything datacenter-related, and (b) high DRAM prices, with most HDDs containing 256-512MB of DDR3. (I haven't physically examined the newest drives - they may be DDR4 and go beyond 512MB; also the 40TB supposedly includes NAND flash, adding yet more cost)