The guy was probably an idiot to begin with, but obviously he took fake news seriously. While people may not be shooting up pizzerias because of fake news, they certainly base views and their vote on some fake news. I don't have relevant polls yet, but this one from last year on many Americans believing Obama isn't Christian is one of them:
https://www.washingtonpost.com/news/act ... 807a0708a1We still hear this view even today, not to mention the birth certificate thing. Hell, even here some have expressed doubt that Obama was born in the US. Also, just take a look at how many people take Alex Jones seriously. I don't deny that people on both sides traffic in fake news or extremely slanted articles to the point where the piece essentially qualifies as "fake," but, and I'd be happy to be corrected here, I don't think the "left" has as strong and efficient rumor/innuendo/conspiracy theory/bullshit/etc. opinion-making machine as the "right" does; then, when you think of the popularity of the folks who fan the flames of these websites/talk shows but don't come out and explicitly repeat bullshit publicly (Limbaugh, Hannity, etc.), then you've got a really strong bullshit-making infrastructure.
You may point to Colbert/Strewart/Bee/Noah/etc. as a counterpoint, but honestly I don't think the analogy works. If Colbert or whomever were called out because they reported a falsity, they would acknowledge the mistake. And even though their shtick is comedic, they still hold themselves to one basic truth: don't expressly spread bullshit. You can't say the same for the bullshit-production on the fake news websites (Obama has issued a blanket pardon to Clinton to insulate her from future prosecution, Obama's grandmother received a six-figure pension, etc).