But how the hell did this happen..? How did Americans people reach this stage of just believing wildly inaccurate stuff they just made up in their heads?

I say people, because it happens all over the world now, we would be foolish to believe this is an American only trait. My own parents voted for the conservatives in SCOTLAND (for context, the conservatives have made it very clear they only care about London and fuck everywhere else in the UK). And when I bring it up they just spout some bullshit about "well rather Boris than Nicola or Corbin". These are well educated, open minded, middle class people... yet their entire vote is basically "I don't like the personality of the other party leaders". Mind boggling...