Then which one is the safest now?
There is no easy answer to this. I would recommend looking at Trezor, Jade, Tangem, Coldcard among others. Do research though.
That can also happen to private keys if we happen to write them on a piece of paper.
Why on Earth would someone do that?
Because the new generation is increasingly aware of crypto, the new generation thief who comes to make a loot, happens to find such a piece of paper could unlock some handsome treasure.