Public Good - a commodity or service that is provided without profit to all members of a society, either by the government or a private individual or organization.
I think your definition of Public Good is rather broad to have any meaning what so ever. Gold is not a public good, it is owned by one person at a time. To claim "the value of gold" is a public good would apply to all goods so as to make your definition meaningless.
Fair enough, I should have explained better what I mean with gold: I were talking about gold as a ledger technology.
Basically I think gold is valuable because it's the most widely recognize universal ledger (the most reliable for now, but I think the ascent of Bitcoin will move that ranking), and therein, the better store of value.
The units of gold are indeed rival. But the discovery of that ledger technology benefited every body, and created tremendous positive externalities.
With Bitcoin the same applies: bitcoins units are obviously rival, but Bitcoin, the protocol, is non-rival.
When I say it is statist I do so because the "public good" argument is used to justify government control over every single "public good" industry. So clearly they want to define it as broadly as possible. They include everything from Roads, to Education, to Healthcare, to Money, to Police.
The Public Good argument is so broad that it consumes over 50% of the US economy as measured by Public Spending.
So when you claim BTC is a Public Good and that mining makes good Public Goods when in reality BTC is a private currency and mining is a private enterprise it shows a huge logical inconsistency which needs to be resolved.
I agree, the term public good is probably more confusing than helping. I'd better say it's a technology which create value by it's very existence. And what allows this technology to exist, and therefore creating the value associated with its own existence, should no be considered a waste.
The next question is: can one create the same value while consuming less resources by tweaking that technology? And my position is that by tweaking the technology you are modifying the kind of value which is created (ie. the two technologies don't served exactly the same human purposes).
The purpose of establishing a new universal ledger is better served by PoW (because of the inerty it creates). And the purpose of leveraging the possibilities open by the blockchain technology, other than the universal ledger function, are better served by PoS.