A lot of people - by nature - are easily led. And when practically 100% of the "information" that comes into their minds through school, media, "news", and so forth is wrong or biased, then such people will be easily led.
Only people who have a thirst for the truth - in any sphere - will do the work that it takes to find the truth. And then there are cynics who say "there is no truth" - but their absolute conviction of such lack of truth is itself a sort of truth, so they are hypocrites.
Just because a lot of people are witless doesn't make the situation ok. And when I say "witless" I don't mean low IQ. There's a native wit or intelligence that means the ability to discern - nay, discriminate - between right and wrong, and it has little or nothing to do with education level or "smarts". And many people have had this dulled out of them, therefore they swim in whichever direction the flow is going.