This mental trap has always existed in the human mind, but now there is an actual infrastructure of information that caters to it, reinforces it, and solidifies it. It is not only the pathologically delusional that can fall into this trap. Now anyone who wanders even a little into the badlands can be consumed by it.
The central problem with conspiracy thinking is that it is self-contained, immune from external reality. Any information can be made to seem as if it supports the conspiracy. Any missing information is being suppressed by the conspiracy, and any evidence against the conspiracy was manufactured and is therefore proof of the conspiracy. If you disagree, you are a dupe, or you are part of the conspiracy.
Higher standards of everyday journalism would help.
One problem, however, is that there is an inherent tactical advantage to not caring about the truth at all. The truth is constraining, and if you are free to make up whatever bullshit serves your narrative, this will make you more nimble in the misinformation wars. It is as if one side is using biological and chemical weapons while the other side is limiting itself to conventional weapons and the Geneva Convention.
This is the problem to which I cannot find a solution. The inherent problem is that it is critically important for society to be free and for the media and speech to be free. How do we simultaneously defend free speech while opposing the abuse of that speech to spread targeted misinformation? The usual answer is, to use your own free speech to spread accurate information. But that just gets us back to the fundamental asymmetry.