You personally don’t know anyone who obviously discloses that they have a safe. If you have a safe you are keeping something valuable secure. The fewer people know that you have something valuable that needs to be secured the better. If people don’t even know your safe exists then that reduces the chances of it being compromised.

I know for a fact that many of my friends don’t own a safe, and I don’t think I’m an outlier here.

I don’t doubt that many people do, but it’s still not a solution for the majority of Apple users.