Large-Scale Hacks can already turn to Real Word Disasters.
If you look at the banking system, how eletricity or water is distributed, or even the shipping industry, we're already extremely vulnerable to hacking attacks that have the power to collapse the entire world in the blink of an eye.
I'm tired of these arguments about evil people locking your door, or driving your car to a cliff.
If you imagine just an average sized city (say, New Orleans) getting its water or eletricity blocked, it will be a zombie apocalypse.