Every event will have its conspiracy theorists. It’s only the official government response to those theorists that fan the flames of their wacky conspiracies.
The US government acted unnecessarily secretive and shady after 9/11. If not for that, Truthers would make up 1/100 Americans instead of 1/4.
Likewise with Obama, if he just produced proper documents instead of forged documents, birthers would disappear.
If the EU didn’t silence any Holocaust deniers’ questions but instead address them, they would largely disappear.
Same thing with the Kennedy assassination.
Conspiracy theorists of these tragedies would largely be ignored if the governments involved would just be more open.
On the other hand, if there is something to hide, better to have 25% believing a conspiracy theory than 100% knowing the fact.