Earlier quoted context omitted.
In the digging example, the goal is to complete the tunnel. If the tunnel is not completed, the project would be a failure. You say that PoW works and makes cryptocurrency doable, yet you conclude that it is a failure. But you don't define what the goal of it is. What specific goal would you want crypto to achieve to falsify your belief that it is a failure?
PoW makes cryptocurrencies doable (i.e. they somewhat work), but not viable . PoW only simulates the creation of value, it does not create it. Yes, sure, fiat currency has also its value made out of thin air, but that value often corresponds to the strength of country's government, economy or fiscal system. Sure, for instance the Yen may become hyper or underinflated, but as long as Japan is an industrial power it's…
There are two notions of scarcity: Scarcity of bitcoin themselves (21 million), and scarcity around being able to create different cryptocurrency. Clearly the only weakness is in the later. Two points on this: Bitcoin commands a majority of proof of work energy. This does tie the digital scarcity of bitcoin to something in the physical world. You can't create another bitcoin without spending a similar amount on PoW. It's not that the scarcity of energy consumed translates to value in bitcoin directly, but rather it gives a high cost for creating an alternative to bitcoin. This is not unlike state issue fiats-- the Yen has value because Japan is a large state. I wouldn't trust a fiat from a state that was just created and had no citizens. So the scarcity of powerful states translates into a scarcity of fiat. Second, Bitcoin was the original invention of true digital scarcity. This makes it a natural place for a focal point. This by itself does not mean bitcoin has value, but it should be better at becoming valuable than other cryptocurrencies.
But bitcoin is also used for transactions and payments. It has growing links to the real economy just like other fiat currencies. The trend here is growing. If the trend continues-- meaning more and more businesses and workers take bitcoin as payment, surely you must conclude at some point bitcoin would then have real value, just like the Yen example?
> Bitcoin is not a real currency, is just a very complicated bank with extra steps, based on an asset whose value basically depends by the biggest Ponzi scheme ever known to man.
I think this is disingenuous-- A ponzi means that through intentional and planned deception invested funds are stolen. Sure, bitcoin is volatile and might crash again. But there is no structured fraud here, it is a free market, nothing like a Ponzi.
You still didn't define a falsifiable goal-- What would have to happen for you to consider cryptocurrencies to be successful, what is the end of the tunnel? It feels to me like you are assuming it will fail (it is a ponzi!), and then working backwards from that assumption to find how to justify it.