We're in the middle of an active cold war where countries are trying to manipulate the citizens of rival countries to destroy their civilization without having to fire a single bullet. Anonymous, over the internet mass manipulation, all for some minimal electricity cost.
AI is particularly bad at this, and regimes that employ tactics generally are not short of labour to have humans to do it.
If AI is being used in these areas it is less as an attempt to manipulate as it is to just create noise and engender distrust in what they hear.
That's definitely the most insidious use, but I think the larger portion is advertisers and karma farmers (who later sell to advertisers).