I don’t think I misunderstood. How fast equipment is “depreciating” is entirely irrelevant, unless you are using the term in a manner I am misunderstanding.

Understanding marginal economics is difficult because it is counter-intuitive. I am currently on a personal binge trying to help understand the economic theory because it helps me challenge whether I have understood and whether I can pass that understanding on to others.

Unfortunately marginal economics is poorly explained - the link I referenced was the only one of five I quickly skimmed that seemed to be free of gross errors and had no misleading content.

Edit: latchkey seems pretty froody and made a couple of relevant comments:

* Bitcoin OPEX (marginal cost) estimation of $7k to $9k per Bitcoin: https://news.ycombinator.com/item?id=31797201

* CAPEX vs OPEX: https://news.ycombinator.com/item?id=31796669