The big costs are the variable costs per chip though, which is why technology shrinks have delivered such great cost savings for the end product despite the fact that every shrink has required ever greater outlays in development costs and capex for the manufacturing plant. The saving in the variable costs are so large that they pay for all that and the price drops.

So even if you have entirely paid off an old fab or bought one outright for ~$0 at a fire sale, you probably won't be able to make DRAM at a hugely lower overall cost. Slightly lower, perhaps.

The figures I found put capital costs as the highest slice of the pie and growing faster than materials or labour costs [1] [2]

[1] http://smithsonianchips.si.edu/ice/cd/CEICM/SECTION2.pdf p. 5)

[2] https://www.icknowledge.com/news/Technology%20and%20Cost%20T... p. 9

I could well be wrong, sorry I should not have tried to make such a strong statement I don't actually have much knowledge of recent technology nodes.

In your first link I'm struggling to see it demonstrate what you say. Actually that's more what I'm familiar with.

Obviously it's quite old though. The second link does seem to show the trend going to equipment costs and trending upward indeed. Although it doesn't seem very detailed, I suppose that first graph on the left on page 9 looks like mostly fixed costs in orange. Thanks for the link.