How often do people get into other's accounts?
There is no specific time period, it mostly depends on the owner's actions such as clicking a malware links, downloading malawares, bad passwords etc...
Do we really need 2 factor authorization? I am not saying we don't; I am just asking.
Yes, we need! It will help us to get a layer of security more. It's not compulsory, it is recommended.
-MZ