I wouldn't call it a scam but definitely overhyped.

The problem is most people (myself included) aren't quantum computer scientists and don't understand what QCs will and will not be able to break in the future. In the common consciousness it might as well be magic, which is why it's good that people like you link reference research papers written by people who actually know what they're talking about.

I'm tired of hearing about QC. It's been like a decade and a quantum computer can't perform a single meaningfully useful computation yet. I remember hearing about how Quantum Computers successfully factored the number 15, only to find out that the system was designed knowing the answer before-hand. Not to mention scaling QCs to large number of qubits seems downright intractable:

While a conventional computer with N bits at any given moment must be in one of its 2^N possible states, the state of a quantum computer with N qubits is described by the values of the 2^N quantum amplitudes, which are continuous parameters (ones that can take on any value, not just a 0 or a 1). This is the origin of the supposed power of the quantum computer, but it is also the reason for its great fragility and vulnerability.

How is information processed in such a machine? That's done by applying certain kinds of transformations—dubbed “quantum gates"—that change these parameters in a precise and controlled manner.

Experts estimate that the number of qubits needed for a useful quantum computer, one that could compete with your laptop in solving certain kinds of interesting problems, is between 1,000 and 100,000. So the number of continuous parameters describing the state of such a useful quantum computer at any given moment must be at least 21,000, which is to say about 10^300. That's a very big number indeed. How big? It is much, much greater than the number of subatomic particles in the observable universe.

To repeat: A useful quantum computer needs to process a set of continuous parameters that is larger than the number of subatomic particles in the observable universe.

yet another confirmation of being super naive, lol https://www.livescience.com/technology/computing/quantum-computers-could-overtake-classical-ones-within-2-years-ibm-benchmark-experiment-shows

Difficulty adjustment happens every 2016 blocks. So if they manage to solve blocks with QC they could snatch all those 2016 blocks before it kicks in. And then difficulty would be so high, that ASICS would never be able to find anything again and the QC would be the only one that finds blocks every 10 minutes.

That would be a hardcore 51% (in this case 100%) attack.

No, it woudn't, because then miners would also start mining using QCs. Difficulty would skyrocket, ASICs would go to scrapyards and network would continue to be secure - you'd still need more compute power to make a 51% attack and double-spend.