That is one way to prevent it from being stolen by hackers online. Although the risk here is on the medium that you're going to use. For instance, a flash drive is one way to store your coin offline. If you decide to use that, you must also consider that a flash drive is still vulnerable to viruses or being corrupted. Even your personal computer may crash anytime and it's possible that you won't be able to retrieve your stored coin anymore.
For me, cold storage is still safer than leaving it online because at least you have the control over how you take care of the storage you use.