What underlying mechanism is the same? decentralized verifiable blockchains has never been used before, especially not in a Ponzi scheme type of application, same goes for linked lists and similar structures.

Forgot to address your first question. I gave a partial answer in an earlier comment above:

Crypto currencies are Ponzi schemes. As with all Ponzi's, to make the big bucks you have to get in early and get out before it all falls apart.

But why do I say "you have to get in early" and so on? First, that's what we've seen; when something goes from less than $1 to tens of thousands of dollars, the Big Money gets made by the early adopters (or investors, if you will). That's not to say substantial profits can't be made later, but going from $1 to $30,000 per coin is WAY different from when the ride starts at $25,000.

And if crypto cannot be made to work as a replacement for "money" -- which is how it's being sold to the public -- and if Satoshi or whomever knew that, then it's a Ponzi scheme; later investors (or whatever you want to call them) are buying in hoping to get rich, money from those later investors IS making the earlier investors rich, and at some point it is fated to fall apart, leaving those who didn't get out early enough holding the bag. I believe this is the case with crypto.

Several factors are hindering crypto currencies and may end them. This post was about the quantum computing issue, but as you know China just recently banned crypto currencies and rumblings about regulating or banning or replacing independent crypto with government versions (yummy!) keep being tossed around. Further, and something quite foreseeable, the incredibly computation-intensive and communication-intensive nature of a large blockchain monetary system can slow transactions enough to become an issue and I believe WOULD become a nightmare if BC were to actually become a day-to-day method of transaction for most people. Right now, Bitcoin use in daily commerce is rare: I have NEVER observed a Bitcoin transaction at any type of store, anywhere. They happen, I'm sure, but I'm saying that for all the shopping my wife and I do, neither of us has ever seen a single person actually USE Bitcoin to make a purchase -- and transaction delays are ALREADY an issue.

The bad news is that this network traffic may produce delays of a few hours to a few days for some users and a wait time of weeks for a small number of users. [bold added]

I believe that these and perhaps other problems will prevent BitCoin and any other non-Government cryptocurrency from ever being viable for general use as currency. I could be wrong, but other than for certain specialized uses, I don't see crypto replacing today's "money." Government versions, of course, might be forced upon populations in many nations; considering the levels of tyranny we're seeing now, I expect that. I don't expect them to work well, even aside from the evil intent they'll be deployed with, but that won't deter the tyrants.