2016 Trump campaign, data was used to stir up FUD and/or discourage voting.
In either case, similar amounts of personal data was harvested from facebook, for whatever purposes the clients cared to use it for, to predictable results.
EDIT: And that's all besides the point - the problem isn't that someone with bad intentions got ahold of data and used in a way they shouldn't have, the problem is people are just getting ahold of data they should not have - period.
How so? Unless they were working with the rest of the media outlets and pushing the "Trump has no chance" / "He will never be the president" story. Do you know of any such campaigns? I mostly see it as a mass media hubris. The same outlets Clinton was expecting to help her ended up undermining the election for her, because, well if Trump only has 1% of winning, why bother putting on the shoes and going out to vote.
I'm not so charitable towards the public.
I wouldn't place any bets that the striking wave of outrage directed at Facebook right now isn't strictly related to the outcome. In this case, that outcome is Trump in the White-house. Not that that isn't a good reason to be outraged - but I don't think its a very principled reason.