I saw a tripod start to go down once due to a slipped leg clamp, fortunately the owner was standing right next to it and heard the "beep beep beep" that a Geodimeter 440 makes when it goes out of level. He caught the gun on the way down, and nothing was damaged. That was almost 30 years ago, and it's the only incident I'm personally aware of that's attributable to a tripod.
I'm not counting GPS antennas that have gone down, as I have a couple of tales like that. Both were two-legged setups on headwalls, and in both cases the operator failed to sandbag the legs, a violation of SOP.
Robotic theft seems like a much more likely scenario to me. There are things you can do to discourage it, but if a determined thief with the right tools wants your robot, chances are he's going to get it.