For one, in my experience when there's a question of whether something was malevolence or stupidity, more often than not it's stupidity, even when coming from high levels of power. For another, extremely large-scale conspiracies would generally require a large level of conspirators to function, which makes secrecy over long periods of time nearly impossible.
We know there have been conspiracies, and there's plenty to point to. Air America, Iran-Contra, the Lavon Affair, MKUltra, NSA domestic surveillance, Operation Northwoods, the Tuskegee Experiments, the Wuhan Lab probability... there's no shortage of stuff like this one could think of that we know happened, in hindsight. But they didn't stay secret, because there's no way they could have.
The incentive structure inherent to participants in what happened under Epstein might make it a unique, special case that has lead to limited disclosures. But in general, there's gonna be some Pentagon papers, Afghan War Diaries, Edward Snowdens, WikiLeak dumps, or some random bumbling of flight records and documents somewhere down the line eventually that'll attract the attention of a whistleblower or journo. Nearly everything comes to light with enough time.
In some ways, advancements in technology make it harder to keep secrets and easier to disseminate them. Everything is digitized and inevitably seems to leak to the public domain eventually. In other ways, I worry eventually AI could become advanced enough that, in the hands of the malevolent, it could cut down on both stupidity and amount of participants necessary.
For other people who, like me, are generally skeptical of conspiracy theories, what have been exceptions for you? Stuff that you think breaks through your general assumption of conspiracy theories being mostly bullshit and easy to dismiss? Like... If you're looking at a scale 1-10, 1 being like, flat earth stuff or reptilian overlords, and 10 being stuff that's probably true but not conclusively confirmed like the Wuhan lab leak or Epstein cover-up for powerful clients or there being something deeper behind the Cuban embassy sickness' stuff... what other things did I not list that you think are close to 10 but that haven't been confirmed as such?