A precautionary ICD is still a significant decision, and it is entirely reasonable to have questions about it. The fact that it has not fired does not mean it is not doing its job.
The device monitors your heart rhythm continuously and records any anomalies, even ones you are not aware of. It provides a level of protection and clinical data that passive monitoring alone cannot. For some people, the knowledge that the device is there also provides meaningful reassurance to both themselves and their families.
If you have concerns about whether your device is appropriate for your individual situation, those are legitimate questions to raise directly with your cardiologist. A second opinion is always an option if you feel your concerns have not been adequately addressed.