> the manufacturing cost is less than five times as much

They don’t manufacture the RAM. This isn’t complicated. They make less margin (a percentage) in your scenario. And that’s what Wall Street cares about.

They don't really manufacture anything. TSMC or Samsung make the chip and Samsung, Micron or Hynix make the RAM. Even Intel's GPUs are TSMC.

Also, Wall St cares about profit, not margins. If you can move a billion units with a $100 margin, they're going to like you a lot better than if you move a million units with a $1000 margin.