QM is hard to visualise, but we have extremely sophisticated equations and principles for determining how quantum systems will evolve, and can engineer complex

QM is hard to visualise, but we have extremely sophisticated equations and principles for determining how quantum systems will evolve, and can engineer complex functioning systems using that knowledge. For example transistors only work because we understand QM well enough to precisely engineer the energy level state behaviour of electrons in semiconductors. It would be like accidentally discovering antibiotics during the plague. You might not know how it works or why, but you know what it does and it absolutely gets the job done.