You think it’s that people literally believe the facts — but these stories are really a measure of how they believe.
I’ll try to make this one quick… Let’s look at some comments selected from below an article from the Snopes.com Facebook page:

The general message, when it comes to extreme and obvious hoaxes, is that many people are utterly incredulous that others might believe blatant nonsense. They’re right to be incredulous, of course, given how blatantly absurd some stories are. But this isn’t the take-home message from these fake stories. Far more importantly, with relatively few notable exceptions, I don’t think people literally believe “fake” news.
To consider if people actually believe them would miss the point, and miss some vital lessons that we could learn from these stories. So instead, we have to treat “fake” news more as fable, or as metaphor. It should be treated as something that is quasi-mythological that speaks to what people believe or, more accurately, what they hold as prejudices.
To illustrate, I’m going to mostly focus on the crap that makes its way around the Lefty-Liberal-o-sphere. You know, the stuff we share around our echo chamber when we’re not plotting to turn half the planet into a Safe Space, convert everyone to enforced homosexuality, or replace Capitalism with Islam.
For instance, just today, I read the story that Dylann Roof has been sentenced to death. Yes, that’s true, and not fake, and is a genuine real news event that did happen. Yet, I decided to remark to someone that he was either going to get executed or given a position in Trump’s cabinet.
Ha! “Lol” as the kool kids say.
Do I literally believe that?
Do I literally believe that a mass murderer would be given a position under the President of the United States? Of course not! That’s absolutely absurd in the highest degree. It’s nonsense – because we all know that, really, he’ll get a pardon and then a half-hour slot on TheBlaze, instead.
Okay, okay… I’ll break with character for a moment and pray to any god that will listen that those two remarks don’t end up on Snopes. No, I don’t literally believe either of those statements. But I said it anyway, not so much as a joke as such, but as a wider comment on the situation that we live in.
Those two remarks do speak to me and what I think. I look around and see a world where if you’re the wrong skin tone you get years or decades behind bars for having weed on you, but if you’re a different skin tone you can avoid jail time for causing multiple deaths – and there are just too many cases to link to of white, wealthy athletes happily getting rape charges dropped because, well, what the fuck do you think the reason is. It’s a rhetorical exaggeration (and evidence of my dire levels of cynicism) for me to say that a mass murderer may well get a promotion out of their racially-motivated hate crime when the rest of those leaders being parachuted into positions of power seem to be racist assholes up may well applaud Roof’s actions or sympathise with him. But it’s absolutely not literal, and I don’t believe it, and it’s not even a case of “Oh, I wouldn’t be surprised if it did happen, lol!!” because I would be surprised and horrified. It is a simple, exaggerated fable.
Today, when we all woke up to the “news” that Donald Trump has been caught on camera doing some harmless watersports with some Russian hookers in Moscow, did we really believe it?
Really?
I hope not. But regardless, it speaks to our prejudices. We look around and we see a world where Trump probably curries favour with Putin, so some dirt on him would be largely unsurprising. We look around and see the potential for corruption (in all politicians, to be fair) and assume this sort of tape or something of its ilk must exist – if not specifically based around hookers and urine. This latest allegation is a fable of “what if?”; what if it were true? What if it was another politician? What if it already has happened and is being used for blackmail? Would we be surprised? Would we have seen it coming? And so on.
(We could use it as a fable to show public moralising over reasonably harmless as presumably consensual sex acts, while remaining silent over harmful and non-consensual ones, but that’s another post entirely and I’d argue it’s a largely academic one so long as this story is as-close-as-philosophically-possible-to-definitely false. It’s also yet another post entirely to discuss it in terms of how it speaks to our fears that our dirty little secrets will get out and society will harshly and needlessly judge us for them.)
In most respects, it’s not too dissimilar a situation to the, absolutely not true I should add, story of David Cameron getting piggy with it at Oxford. Do we literally believe it? No. But that story spoke to us about our distrust of the ruling classes, their clubs, and their unfathomable privilege. Anyone with a strong bias against David Cameron and the culture he came from may well consider it believable, but not necessarily believe it, but above all it would be a fable of how they see the wealthy ruling class of Britain. They see them as living in a world where such acts are “japes”, that it can be covered up and used as revenge and blackmail in their dodgy dealings, and the myth, the story, the fable vocalises those fears better than any description. It’s possibly even a better description of those feelings than even a true story.
As a result, you need to look at false news and its spread not as merely disinformation. A false meme isn’t going around that could easily be displaced with the truth. After all, people don’t readily alter their opinions based on new evidence – they’ll just warp their reasoning around the new evidence to keep it. So simply providing the real story won’t help – because that assumes the problem stems from whether people believe it or not, when it doesn’t stem from that at all.
Fake news, then, should be considered more as a barometer for peoples prejudices and prior biases. It should be used to judge how they think the world works, or at least how they think it should work. Fake news tells us who people fear and why, and what they find most pertinent to be scared of. It shows us what they wish was true about the worst parts of society, and what they want to project on to them whether it be due to fear or anger.
Or, maybe, I’m entirely wrong and people are just gullible idiots. And I don’t know which of those two options is worse…
Addendum: I just want to append a quick rant here. While I’m happy the idea of “fake news” is now going a bit mainstream and precipitating a near-global conversation, I want to point out that skeptics and rationalists have been saying this for years, if not decades, if not centuries. This isn’t some “I did it before it was cool” argument, it’s because each time we were shouted down as irrelevant killjoys. “What’s the harm!” you’d hear people cry. “But let them believe what they want!” Well, here we fucking are. Years of letting people get away with living in their own version of reality has brought us to this. Lies upon lies upon lies have been built over mounds of bullshit formed on foundations of utter bollocks and now we might get to see some unfortunate consequences as people have built entire universes out of shit and nonsense so large, so inter-connected, so impervious to reason, that they are literally impossible to shift. Thanks for that, you stupid fucks.