[gritzko]

You are focusing on a single scenario of an individual double-spender. Why don't you consider some other scenario, e.g. a hacker getting control of a major BitCoin mining facility to disrupt things just for a laugh? I've seen a lot of that happening. There are tens of possible scenarios. Mining capacity is highly centralized these days and that trend will likely develop further (see the subj). The mental model of "one malicious node against all the honest nodes" is totally bogus.

So far, my observation is that BitCoin can't run cheaply on the reasons already mentioned. I will only buy your argument if you'll show me a graph of power consumption vs turnover and it will happen to be sub-linear.

[CyberDildonics]

If a miner gets hacked, then their blocks will go to the attacker, or they won't be mining. Blocks will be mined more slowly and transactions may take longer for the same number of confirmations until the miner comes back. If a bank gets hacked, people steal money enormous amounts of money by directly changing their ledgers. I don't see this as some sort of a loss for cryptocurrencies.

I'm not sure what you mean by turnover although you might want to learn more about bitcoin before you rail so hard against it.

[gritzko]

Turnover: the amount of business transacted during a given period of time. How much BitCoins change hands in a month, for example. Actually, plotting that in dollars is even more correct, as electricity costs are not paid with BitCoins.

Ultimately, that is a graph of dollars moved vs dollars wasted. (I explained the difference of "spent" and "wasted" in a different comment.)