The attempts to build "qubits" involve very complicated custom gadgets, with strange crystals or superconductors, or other weird things I don't know much about.

The attempts to build "qubits" involve very complicated custom gadgets, with strange crystals or superconductors, or other weird things I don't know much about. And then refrigerated down to almost absolute zero. And it's not just about mass producing qubits, they need to talk to each other, ie. be entangled. And that is the really hard part about all of this.