The odds vary based on location. In a secured area (can't be reached without passing through a locked door) then it's crazy low or zero. If it's on a public street it's higher. If it's in a secure space the odds are far higher (inside a shop for example). Security devices installed by staff as a part of a build will never disappear.
Why? Because it makes sense to me that ambient population (greedy, poor, angry, WCS and others) can and would remove or destroy security devices they can get to. Also, massive networks can, in my opinion, be stifling and some locations should simply never have cameras for any length of time for game balance or OOC game health reasons.
Once this is set up and well tuned staff can largely stop worrying about watching camera networks for balance issues as they will generally self correct over time once the odds are dialed in.