Trustworthiness always depends on your use case.
If you are transacting small amounts of money (less than is spent on mining a block) then waiting for 3 confirmations is probably sufficient to consider the transaction settled. But what if you send a transaction with a 100 times higher value than goes into mining a block then you will need to wait for over 100 confirmations till you can be sure it doesn't make economical sense for anyone to try to double spend your transaction by orphaning the first block your transaction was in (with a very simplified incentive model not taking into account other transactions in these blocks).
Thus the money spent on mining blocks determines how much value can be transferred in one block. Allowing for higher value transactions is good thing imo, is necessary for its success as digital gold and therefore justifies the higher energy consumption (especially since there don't seem to be any alternatives with similarly good or better robustness against attacks yet, proof of stake can't work under the same assumptions bitcoin does [1]).
> Allowing for higher value transactions is good thing imo
PoW systems are the only ones where "higher value transactions" need security proportional to their size.
> PoW systems are the only ones where "higher value transactions" need security proportional to their size.
Every other currency is either backed by men with guns and transactions are reversible (fiat) or you have to spend a roughly proportional amount of resources securing it (e.g. gold). I didn't look at the data, but judging by US military spending I'd guess that the strongest economies also have to spend the most to keep their system safe.
You can still argue that the assumption of pseudonymous actors in bitcoin makes the proportion factor larger (=system less efficient) than for systems that can use identities and attribution and I'd agree with that. But that's only because it can operate with less assumptions (no identities), which I see as a feature.
So what? Men with guns are also the foundation of property rights, law and order, and national sovereignty; they are not an extra cost of fiat currency, they underpin the government's ability to maintain order and structure within society. I shouldn't have to explicitly point this out.
> transactions are reversible (fiat)
Cash payments are not reversible. Reversible payments are also a feature that nearly everyone wants.
> spend a roughly proportional amount of resources securing it (e.g. gold).
Gold is not a currency.
> that's only because it can operate with less assumptions (no identities), which I see as a feature
Untrue. A centralized anonymous payment system is technically possible, the limitations are strictly legal.
It was for millennia.
I can't imagine the processing being done by my computer right now is all strictly necessary to read and post these comments, and I'd wager this site is more efficient than most these days. Still I accept reality and pay these costs in order to talk with you on the internet because this is the world we live in. It looks like these nice people at MIT are working on some of the inefficiencies of cryptocurrencies, so let's rejoice.
Yes, that's exactly the point. Bitcoin is insanely inefficient because PoW is insanely inefficient. Unlike other "inefficiencies" where there is a logical relationship between "energy spent" and "useful work accomplished", with PoW there is no such relationship since the energy isn't spent doing useful work (i.e. processing transactions). Yes, more power into the network makes it "more secure" by making it "more expensive" to perform a 51% attack. The increased expense is distributed across the network in the form of increased difficulty. If a 51% attack was already implausible (which most bitcoin enthusiasts would say is true), then making it even more expensive doesn't actually do anything useful.
Trust-less consensus may be the same. Nature doesn't care either way.
Well it depends what you are considering. Arguably, yes, your computer finished the HTTPS connection long before you got around to reading the words on the page itself. But the scale of an idle CPU compared to a 100% CPU is not even close. Mine is sitting at 2% use while I type this.
You could put that money into mining actual gold, and literally make 4x as much as mining bitcoin [0].
[0] https://www.theguardian.com/technology/2018/nov/05/energy-co...