The most Occam and probability theory compliant explanation for most conspiracy theories is they are bullshit spread as part of a single umbrella psyop. The goal of that umbrella psyop is that THEY want to erode your trust in facts, news, and experts. They know that trust eroded you will give up and stop fighting back or beg for increasing top down controls over everything to restore sanity.
Discussion
I don't understand what you're saying but i will fight with my last breath for your right to confuse me
ELI5 version. Confused people are easier to manipulate. Conspiracy theories are spread by the government to confuse you so they can manipulate you better.