Just as some people are susceptible to lies, others are impervious to them. The real question is: What makes these people so different? Libraries have been written about the psychological failings of the former and the strengths of the latter. And it basically boils down to this: the former personalities are lacking something that must be filled by someone else; the latter have an ethical foundation on which they can confidently rely.
Human beings, like newborn ducklings following their mother, are impressed at childhood and that formative impression, good or bad, is very difficult to change. There is nothing to be gained by “arguing” with the conspiracy minded; paradigms rarely shift, they must instead die out on their own.
Unfortunately, it’s a race to the finish line, and it’s not at all a sure bet that rational runners will win.