The first reason you need a cold storage device is because you want a private key generator that you can trust. Second reason is because you need something to get bitcoin off the exchanges. How do we achieve this easily for the masses?
Discussion
Storing your own Bitcoin keys isn't easy, but it's worth it.
You don't need private key generator to trust😉.
I trusted my dice (256 times).
Then I crunched numbers using pen and paper.
🧡💜
https://bitcoinmagazine.com/culture/diy-bitcoin-private-key-project