Well, you guys should study history of money and definitions better.
'Backing currency with something' means you can convert the currency back to a pre-determined amount of the underlying asset, that's why it's called 'backing'. You can't convert Bitcoins or any other PoW currency to a pre-determined amount of energy any better than you can convert a PoS coin. The only value a coin has is utility value, which is what it can be used for. The more functions the coin has, the higher the utility value, and that's how the price is discovered on the market. The argument of 'PoW is backed by energy' doesn't hold water.
Gold also can not be converted back to the energy that were used to mine it. And gold's price are mostly decided by those energy (manufacturing cost)
It does not matter you use gold or use some paper(usd) or use a string of text to work as currency. The purpose of all currency is to act as a unit of value, so that they can be used to purchase goods/services with corresponding value
So where is the currency's value comes from? It is usually the manufacturing cost. If one ounce of gold cost only $10 to mine, can you sell it at a market price of $1200?
When people produce goods/services and get paid with the currency, the value of the currency is corresponding to their work, so it feels very fair and natural that everyone must work to get money, including those who produce money, all the value creation process must be equal
(Fiat money is an exception, it has value because all the people are forced to use it at its face value, but its value is based on a consensus)
this is a pointless argument.. all nxt coins were produced for free.. yet it has 5th? highest marketcap.. this proves that zero production cost DOES NOT mean that it has no value/price. this is a perfect example of cost free production + limited supply + utility + demand = value.