The confusion for many people stems from how security is achieved for blockchains. Most systems have an identifier and a password, and sometimes 2FA. For bitc

The confusion for many people stems from how security is achieved for blockchains. Most systems have an identifier and a password, and sometimes 2FA. For bitcoin, all you have is a 256 bit key. The key points to a 160 bit address (through hashing), and allows signing transaction from that address. This is true security by statistical obscurity, as you can generate as many keys as you want by brute force, and all of them will match and give you control of a valid address, with a non-zero chance of it being an existing address with a balance. The chance is so low that it is completely acceptable though, at around one in 2^154. This means the bitcoins people own aren't materialized, you can't delete, download or store them. They are simply a positive balance recorded on the blockchain for an address they control. There is no cold storage for the coins, as they are always publicly available on the chain, and anyone with a valid key to that address can spend them. The only way to lock them down is to move them to an address that only you control. When people talk about cold storage, they're talking about the private key. You can generate and store a key on a secured machine / device, allowing you to generate signed transactions for the corresponding address. You then copy that transaction to a internet enabled machine in a secure way, and broadcast the transaction to the network.