Yeah, let's be real. If something as simple as basic facts about the Maya was enough to sway these people, we wouldn't even have this thread.
I think the reason why people buy into conspiracy theories is that they feel special, they know.
I've talked about this before a bit. At least in America, I think a lot of conspiracy theories, especially those on the Right side of the spectrum (The recent "Mass shootings are a false flag to take away our guns" conspiracy theory would be a good example) come from America's roots in rebellion against a foreign power, and all that crazy rhetoric about trees and tyrants and blood. On the left, we've got Vietnam and Nixon and Cheney and all that shit convincing people that the government's up to no good, and in the end you have a society that treats it as a matter of course that the government is no longer acting in society's best interests. When that idea gets into the right kind of brain, you get conspiracy theories.
Post-catastrophe theories like these shooting ones, and 9/11, I think come from a just world hypothesis. Long story short, people whose worldviews don't allow for absurdity attempt to recontextualize the event so there's a tangible bad guy who can be fought: the government.