You're right, I've left a lot out here for simplicity. I've ignored that miners have costs other than electricity, that miners buy their electricity for cheaper

You're right, I've left a lot out here for simplicity. I've ignored that miners have costs other than electricity, that miners buy their electricity for cheaper than the average american, that most miners make a profit, that currency exchange markets have friction, that miners provide a more valuable service to the network than creating coins, that the average block has less than 2000 transactions, that it is possible to fit more than 2000 transactions into a 1 MiB block, that the current price reflects expectations of the post-halvening future, and so on. My estimate could be half or double the real number, though I think it is in the right ballpark. I really wanted people to take away two things from that comment which I'm not sure I got across: 1) The cost (in money and energy) of each transaction will increase as the value of each coin increases, and decrease as the number of transactions per block increases. If we assume that the number of transactions will increase faster than the value (which I think is a reasonable assumption), then the cost per transaction will fall over time. 2) When all 21 million coins have been mined, the block reward has tapered off to zero, and miners are dependent on transaction fees, the cost (in money and energy) of each transaction will be much lower than today. You can think of the energy currently being burned on mining new coins as being the tangible asset which backs those coins.