1) Trump had a significant chance of winning because of a disgruntled American public voting against establishment candidates (the same reason Obama himself was elected in 2008).
2) There was "fake news" before the election.
Indeed, I know a number of additional things.
3) Right now there is a crisis in faith and credibility in the US domestic news. The reason for this is that the official narrative across the media industry - much of it literally state propaganda - has been consistently proving hallow and unreliable. People are continually confused, and their attentions are jerked around as the media needs the public to be outraged/motivated/mobilized at each subsequent juncture.
4) There is huge amounts of fake news and misinformation INSIDE the industry. If you want to focus on Trump rather than national security and propaganda, take the ubiquity of the "search terms spike for how to move to Canada after Trump won primaries" with absolutely no coverage giving the context that Canada had on that day finally passed a long-in-revision piece of legislature revising US-to-Canada patriation and such search terms would have spiked regardless of the candidate in the US primaries. (Trump is not and never was a candidate for president that I would endorse.)
5) The "fake news" surge is a grasp by establish monopolistic forms of misinformation distribution to maintain their domination and credibility as sole sources.
