Storage devices use to hold information. In spite of how much for the hardware, the data itself is the most valuable asset.
There are many ways to lose the stored data, for example:
The drive or storage media can fail or be damaged
An accidental data deletion may occur
The data can be (erroneously) deleted intentionally
Your computer can be hit by a virus
And, if the damage to your data is irreversible, then a permanent data loss occurs.