Lot of people posting their Steemit articles here trying to make bank.

Anyway, this is common sense. TRUE COLD STORAGE = PAPER WALLET
Anyone who lost a significant amount of Bitcoin will tell you a paper wallet is the safest way of storing it. Think of it like cash money, except you are holding a paper with your keys on it. No one can hack you if you use this method.
To break can not, but you can lose the keys. If you store them on the computer then hack your PC and steal your codes much easier than to hack e-wallet. I think that in General it is impossible to store a large amount of bitcoins in one place.