Why big tech shreds millions of storage devices it could reuse
ft.com
ft.com
I would trust an ex server-room hard drive for continued use just as readily as I'd stick a bunch of thumb drives to handle storage expansion on the same systems. I simply wouldn't. And literally for the same reasons.
Besides, look how cheap 3Tb drives are these days. Just opt for security and shred your old drives. I drill mine open and then burn the platters. Except the glass ones, 'cos they usually are already shattered by the time I get the case open.
PS: Keep the magnets. They're really powerful. My fridge has a lot of them. They'll hold your calendar and kid's art way better than any usual magnet you'd buy for that. The DIY folks have even better uses for them.