When it comes to thinking something didn't happen, how do you explain all the witnesses and testimonies after, often from people who are 3rd person? Maybe someone paid off all their families too?
As for HOW things happened, that is often depicted by the ones with the loudest voice, the news makers, the story makers. That is why they call them stories after all, the more meaty they can make it, the bigger the story.
Even with all the proof on 9/11, even with all the proof for multiple shooters in Las Vegas, people believe the loudest voice to be the truth (even if they think maybe it is, maybe it isn't). Conspiracy theorists are most often story tellers themselves, and like news, not truth tellers.