Conspiracies that require absolute lock tight secrecy to function at a basic level aren't generally tenable to be sustained for longer than a handful of years at a time at most. Somebody always fucks up or basically was just lucky nobody checked for awhile. The nessesity of any large scale collaboration creates inefficiencies and potential error points in the system. Even the best of the best spy agencies fuck up and get caught rather routinely, particularly when operating on their home soil. A lot of investigative journalists accidentally trip over stuff all the time but have good faith arrangements (or in some places laws) to not disclose the active manoeuvres of the state to the public.

It's just really hard for humans in general to accept that events that effected them or things they care about very deeply personally weren't somehow also grand in design. Grocking sometimes it really is just random chance or stupid mishandling is not something we're well wired to handle. Stories of all powerful conspiracies masterminding the world scratch that itch... But logistically speaking the conspiracy aspect is completely unnecessary. If someone is trying to blame a nebulous bogeymen who exists as nameless, numberless ultimately wealthy but also totally off the books super spies.... chances are they are just trying to capitalize on making you feel flattered, smart and empowered by something "only you are smart enough to believe" - while feeding you bullshit they can personally profit from in some way with you none the wiser.