Comment by Thorrez

>The entire idea behind POW is that the total amount of work must be in direct relationship to the total value of the coins in the network, or else coordinated attacks become possible.

The total amount of work must be in direct relationship to the amount an attacker can gain from executing a 51% attack. It's not clear to me that if bitcoin doubles in price, an attacker can gain double the amount from a 51% attack. A 51% attack doesn't allow direct theft of other people's bitcoins. It allows double spend attacks, denial of service attacks, and through those, the ability to tank the price of bitcoin.

>Just think about how your "If it's using Europe levels of electricity at time X, then after a block reward decrease, it'll use Europe/2 amount of electricity" sentence doesn't make any sense, because eventually in 2140 or so there will be no block rewards, so according to your logic no electricity at all would be required to run the network.

It's possible for a block reward to be larger than necessary for security. In that case it can go through several halvings that purely improve efficiency without putting the network at risk. Yes, at some point, with a sufficiently large number of halvings, the network would be at risk, but that doesn't mean we can't have some efficiency gains before that happens. Your previous comment referred to bitcoin using more electricity than Argentina. That's a statement about how much electricity it's currently using, not a statement about how much electricity it needs to use to get the necessary amount of security. It might be possible to decrease the electricity usage while remaining sufficiently secure.