A person, moving a magnet near a single wire - not even a coil - is going to induce utterly insignificant amounts of electricity.

You'd need lab equipment to even detect it. It will do absolutely nothing whatsoever to computer electronics.

- HDDs often live right next to each other (separation of roughly 1cm, front to back).

- Power supplies and their induction coils are right next to the drives in some cases, including for instance consumer grade NAS boxes.

- HDDs tend to have a coil of wire, too.

If HDD magnets overwriting nearby HDD data was a thing, it would be happening all the time.

If HDD magnets in motion in certain orientations were inducing damaging currents in nearby HDDs or in nearby power supplies which then damaged connected components, that would be happening less often but still all the time. Not all chassis designs have power supplies at the opposite end as the disks, and some applications like consumer NAS boxes have them in close proximity to each other.