this does not explain something like the manhattan project.
its not necessarily time that real science and engineering takes, but resources.
there's lots of fast progress happening in areas that get a lot of resources invested into them, and much slower on areas that dont have financial champions. moving fast doesn't necessitate that something is a scam
Sorry, I'm not sure I follow what the disagreement is? I don't claim that moving fast necessitates that something is a scam.
In any case (and I don't think this bears on your point, it's just something I'd like to add), building a quantum computer is very unlike building a nuclear fission device. Echoing my other comments here, it's almost misleading to call it "building a quantum computer," as that puts people in mind of 'unlocking' some single discrete technology in a strategy game tech tree. It's not that at all; it's a huge umbrella of (in many cases) extremely sophisticated technologies. The Manhattan project, as complex and astonishing a feat as it was, was a little closer to the strategy-game vision of research in that way. There's a reason it was possible in 3-4 years in the 1940s!