For example, I've given the WPA2 password to many people; and that can be used to snoop on it passively (there's no forward security).

Modems are anyways way more insecure due to the default password being admin or 123456, etc. And many are accessible from the public internet.

I think my modem got hacked due to that (I saw some login attempts a little before the DNS got changed causing Youtube to stop working).