You will find that very often the scams, advice, self-help, doctrine, etc that draw these populations have one thing in common: if whatever it is doesn’t work, it is because you are doing it wrong, not because the guidance is bad. That’s why conservatives will defend the tax rates of people who have 5 orders of magnitude more wealth than they do - they believe that it is their own fault they aren’t rich, and that anyone can become rich if they just try hard enough. It is why religious conservatives will still attack birth control in the face of their own kids having unwanted pregnancies. It is why natural medicine people will defend their practices even after it sends them to the hospital. They are more willing to believe that they themselves are at fault than the principles they believe in.