Some people are a bit thick. They know this in their hearts, that whatever they are capable of, there are other people who are smarter, quicker, better at things than they are or seem to be appreciated more for what they can do. For all they can do, there's something they can't quite put their finger on that means they just can't do quite as well, whether it's at work, at home, in the pub - they feel that there's something missing, something just out of reach and if they could only reach that thing, every part of their life would improve. They're permanently dissatisfied but for whatever reason, they aren't able to make changes that would improve their lives.
And then something comes along that more people don't understand or can't control. The experts can't give all the answers, the information is constantly changing, politicians do what they do best - influencing people. Everything's in flux, nothing seems stable or secure and that uneasy feeling that there's something missing spreads to more of their life and it feels as though everything is running out of control.
Those people then hear somebody whispering in their ear (through YouTube or social media because they're looking for answers). 'It's not you, it's them. They're the ones responsible for your misfortune. It's not your fault, They are sneaking around behind the scenes deliberately working to screw you over. And now they're doing it in plain sight, they're so confident that nobody has seen them for what they are, mocking you' Wait, what? Who's 'They'?.
And the answer (The Chinese, Jews, Muslims, Left leaning politicians, communists, doctors, huge companies that make more money than they could ever comprehend - whether faceless corporations or charismatic/influential CEOs - etc, etc) makes sense to them. There isn't anything lacking in their abilities, personality or circumstances. It's not their fault, it's somebody else. Like the feeling that there's some secret thing that's held them back in life and kept them in a dissatisfying environment, that secret thing is a symptom of the same going on at a worldwide level. And this whisperer has given them this information. This information is a big secret that they're now ready to hear. Because they're special. They're worthy of this information. They're the key to stopping this; the Only Hope. They are the Chosen Ones.
Some will proselytise, to share the secret, to be treated as the expert, the one with the knowledge, some will retreat into planning to be the ones who come out on top and to be hailed as the ones who knew all along. They watch vlogs, they read, they listen to people confirming their view, they see more and more that feeds their self image as being the ones who knew. When facts get in their way, well, you just have to believe, those facts are there purely to lead you astray from 'the truth'. Only the Faithful will survive. You gotta have Faith.
500 years ago, scientific facts would be interpreted as The Devil putting doubt into their head. And you have to cast the devil out. They've likely grown up with some cultural religious conditioning where they sort of know at some level that Faith in the unseen defeats Evil.
The key to manipulating them is convincing them where Satan is hiding. And centuries of Antisemitism is pretty useful for that; there's two millennia of cultural works, of religious imagery, of plays, of books, of films, of cartoons, all ticking away in the background, telling them that Evil is always there, stealing their success and happiness. And if that's not enough, you can throw in Anticatholicism/Protestantism/misogyny to convince them that everything is the fault of Somebody Else who is deliberately, malevolently acting to ensure that the person hasn't achieved the acclaim and success/wealth/power/sex/adoration that they feel they deserve.
They see 'Satan' everywhere. They just don't use that name for the concept. They use Bill Gates, Big Pharma, men who they can't understand having a life they feel they deserved, women who would never want them, different ethnicities, different beliefs.
Religion and the concept of personification of Why Bad Things Happen is a fundamental of the human condition. And whilst some, most, can see that sometimes Shit Just Happens (and other people being a rubbish makes it worse), these are the ones who want to be burning witches, sacrificing others, casting the Devil out. Because the alternative, that Shit Just Happens and sometimes, there is no other reason for failure than You're a Bit Crap, Really, is too much for them to bear.