I put the word "some" in front of "crypto" for a reason.

There is some crypto that we know how to break with a sufficiently large quantum computer [0]. There is some we don't know how to do that to. I might be behind the state of the art here, but when I wasn't we specifically really only knew how to use it to break cryptography that Shor's algorithm breaks.

[0] https://quantum-journal.org/papers/q-2021-04-15-433/

Nope. Any crypto you can break with a real, physical, non-imaginary quantum computer, you can break faster with classical. Get over it. Shor's don't run yet and probably never will.

You are misdirecting and you know it. I don't even need to discredit that paper. Other people have done it for me already.

This is incorrect. Whilst you may be sceptical about whether quantum computers can be realised, the theoretical result is sound.

Recent advances in quantum error correction are a significant increase in confidence that quantum computers are practical.

We can argue about timelines. I suspect it is too early for startups to be raising funds for quantum computers at this stage.

Source: I worked in quantum computing research.

Shor’s algorithm can. What is speculative about that?