[quickthrower2]

For currency: the fact that it is quite difficult for an average person to keep their keys both secure and backed up. For example choosing a secure enough but memorable password for their wallet. Not having their PC hacked while they type in such password etc. As the currencies go up in value so will the sophistication of attacks.

For other applications: Miners fees are high. Any data put into the chain is public and immutable and probably stored forever. So even encrypted messages may be attackable at a future date and the secrets leaked. So you want to stay anonymous there can't be too much interesting data stored in there.