Or, maybe people just aren't good at scope-limiting their cynicism.
The people physically close to you probably want what's best for themselves and those around them. They're good people. You could probably trust them with your life, provided your emergency is happening right in front of them (and they know what to do about it). The people you talk to online, the people who produce mass media, and the people who write your school textbooks? Never. Drop. Your. Guard. The average person doesn't want to hurt you, but these aren't the average person.
Heck, the mass-media people don't even need to want to hurt you to hurt you, as Michael Crichton once said:
> Media carries with it a credibility that is totally undeserved. […] You open the newspaper to an article on some subject you know well. In Murray's case, physics. In mine, show business. You read the article and see the journalist has absolutely no understanding of either the facts or the issues. Often, the article is so wrong it actually presents the story backward—reversing cause and effect. I call these the "wet streets cause rain" stories. Paper's full of them.
> In any case, you read with exasperation or amusement the multiple errors in a story, and then turn the page to national or international affairs, and read as if the rest of the newspaper was somehow more accurate about Palestine than the baloney you just read. You turn the page, and forget what you know.
> That is the Gell-Mann Amnesia effect. I'd point out it does not operate in other arenas of life. In ordinary life, if somebody consistently exaggerates or lies to you, you soon discount everything they say.