It does not matter pow or pos, as long as the coin generation has no cost, the exchange rate will be close to zero. If you want to give a cryptocurrency some value, it must have a cost
It seems that fiat money does not have a cost but still have some value, but fiat money is forced by law into circulation thus backed by all the merchants' productivity in that country, thus the cost is the cost to make that law: A war or lots of political campaign could bring such a privilege, they cost a lot
But for a cryptocurrency, you can not force them into circulation, thus its value is closely decided by the manufacturing cost, just like gold. Of course the market demand will affect the exchange rate, but cost is always a baseline for deciding its value: If it cost nothing to make a $500 coin, everyone will immediately dump their coin into market, thus the coin becomes a pump and dump speculation
Suppose that 100 coins mined per day, there might be a shareholder using $50000 to buy up all the coins everyday to artificially maintain a market price of $500. Then its market capital will never grow big enough to take serious volume
However, if those 100 coins cost $5000 to mine, then the producer will refuse to sell under his cost thus automatically reduce the sell pressure on the market when exchange rate dip below $500
I would argue that purely PoS coins do cost something. The different ways of distribution for PoS/consensus I have seen all cost the person who originally received the coins something, except for one distribution model.. giveaways.
The 3 distribution methods where the coins cost money:
IPO - Definitely costs $$$
Proof of Burn - Definitely costs $$$
PoW period then switched to purely PoS - Costs money in the electricity used and time mining in which someone could of mined other cryptocurrencies
The only sketchy non-PoW distribution model that this argument could possibly be applied for:
Giveaways - I admit this is the only category thus far that could fall under your reasoning above, however giveaways have costs in that it takes the developers time, energy, and money, to program and market the cryptocurrency. However, is this perceived cost enough seeing as though the end users didn't pay for these costs themselves? Maybe, maybe not.
In the case of generic country coins that bring no innovation to the table, they have failed on a massive level. In the case of Ripple which bring an innovative approach, it has sustained and even grew in value. I think some cases are different than others, and cost is not an end all be all to a cryptocurrency having value. As long as the crypto provides some benefit, utility, or innovation, AND a larger cryptocurrency isn't already known for this innovation, then it is possible for it to survive and possibly even thrive due to the network effect.
I get what you're saying, but I'm not sure it's actually true or not. I agree my reasoning for giveaway coins having value is somewhat sketchy, so feel to prove me wrong. I have actually been using this as a reason as to why I think "spin offs" will not work, because I think Bitcoin holders will dump immediately for profit just like the country coin failures. So I guess I am contradicting myself here... I admit it is complicated.
Although to be fair to my reasoning as to spin offs, specifically the spin off I think is likely to fail is Aethereum. It is mostly due to your reasoning that there is no costs, combined with the network effect of Ethereum in which everyone pretty much sees as the decentralized programming project to beat. So in combination of no cost and the network effect, I think Aethereum will not do so well. If you replaced Aethereum with some innovation or improvement upon Bitcoin that has not already garnered a network effect, it may be possible for the spin off to be a success. I think Stellar will fail for the same reason, there is no cost and Ripple has already achieved a sufficient network effect.
So in summary I suppose I believe that my theory for other giveaways holds true with Spin Offs: As long as the crypto provides some benefit, utility, or innovation, AND a larger cryptocurrency isn't already known for this innovation, then it is possible for it to survive, and possibly even thrive due to the network effect.