We have had it already, several times over but people dont care. Once it is something big enough (like I now own your house or bank account) people will care, although big bank and government will protect us surely...
I wish I were a hacker capable of such feats.
Or constantly toggling things that require power in sync, which would throw off the power grid system in some way.
Or making food rot in fridges.
Or randomly flashing lights on during night, interrupting people sleep.
There are many ways that some of those things can be statistically dangerous or life threatening at scale, either directly or by consequence.