Having lost the popular vote, but winning the presidency with a margin of 77,744 votes in specific locations, it is not hard to imagine that Trump's success could have been thanks to carefully targeted political ads.

https://www.washingtonexaminer.com/weekly-standard/the-elect...

Of course it's impossible to say whether Trump would have won even if he hadn't spent any money on Facebook ads, but we're talking about a campaign that spent hundreds of millions of dollars in total. If this amount of money doesn't include enough to influence 78k people to go out and vote for a specific candidate, then we might as well give up on the very concept of advertising.