Here is my analysis of the probabilities for the various conspiracy theories you mentioned, along with brief justifications:
Epstein was murdered 1 in 5 The circumstances around Epstein's death were highly suspicious and convenient for many powerful people. However, incompetence and negligence in prison are also plausible explanations.
JFK killed by someone other than Lee Harvey Oswald 1 in 10 There are still many unanswered questions and odd coincidences around the assassination. But the case for a conspiracy is not definitive and Oswald remains the likely sole perpetrator based on the available evidence.
9/11 inside job (they were trained by the CIA) 1 in 1,000 While there are some curious links between the hijackers and US intelligence, the evidence is far from conclusive. Such a vast conspiracy would be very difficult to coordinate and conceal.
9/11 inside job (controlled demolition) 1 in 10,000 Scientific analysis has consistently debunked controlled demolition theories. The collapse of the towers matches what would be expected from the plane impacts and fires.
9/11 inside job (holographic planes) 1 in 1,000,000,000 This theory completely defies Occam's razor and is not remotely supported by any credible evidence. It would require absurdly advanced technology and a near-impossible scale of deception.
9/11 (Israel Responsible) 1 in 1,000 This theory lacks credible evidence and is often rooted in anti-Semitic tropes. While some individuals have claimed Israeli involvement, thorough investigations have found no supporting evidence.
Flat Earth theory 1 in 1,000,000,000,000 Every line of scientific evidence, from photos from space to the easily observable curvature of the Earth, conclusively disproves flat Earth theory. It has zero factual basis.
Hollow Earth theory (technological civilization underground) 1 in 1,000,000,000 Seismic data clearly shows the Earth is not hollow. A massive underground civilization is not consistent with any geological or scientific evidence.
Moon Landing Hoax 1 in 1,000,000 The sheer scale of evidence for the moon landings, from independent verification by other countries to analysis of moon rocks, makes a hoax absurdly implausible. The "evidence" for a hoax does not withstand scrutiny.
Jesus Never Existed 1 in 100 While the supernatural claims about Jesus are debatable, his existence as a historical figure is supported by most scholars based on independent extra-biblical sources. However, the evidence is limited enough to leave room for some doubt.
The Nazi Death Camps were hoaxed (No mass gassings, no Jews gassed) 1 in 1,000,000,000 The historical evidence for the Holocaust, including documents, material remains, meticulous Nazi records, and thousands of corroborating eyewitness testimonies, is overwhelming. Holocaust denial defies all facts and reason.
Jews were mass resettled in USSR in WW2 and there was a cover up there 1 in 1,000,000,000 Millions of Jews are simply missing from Europe based on all available demographic data. Any mass resettlement program of that scale would be impossible to cover up and there is zero credible evidence for it.
6 million is a magical number for Jews 1 in 1,000,000,000 The figure of 6 million Jewish Holocaust victims comes from meticulous documentation and demographic analysis. Earlier unrelated uses of this symbolic number by Jews do not undermine the factual basis of the Holocaust toll.
Katyn was a German crime 1 in 100,000 Russian documents released after the fall of the USSR clearly show that Katyn was a Soviet NKVD crime, which Russia has now admitted. The evidence clearly contradicts the Soviet narrative blaming Germany.
Rape of Nanking was 99% hoaxed 1 in 1,000,000 The scale and brutality of the Nanking massacre is attested by numerous eyewitnesses, photographs, foreign observers' reports, and even some Japanese veterans. Any exaggerations do not discount the essential facts of the atrocity.
Armenian genocide didn't happen 1 in 100,000 There is ample contemporaneous documentation by diplomats, missionaries and journalists corroborating the basic facts of the genocide. There is no serious historical debate about the reality of the event, only its qualification as a genocide.
WW1 "stab-in-the-back myth" is true 1 in 1,000 German military leaders spread this myth to deflect blame, but the German army was genuinely collapsing by late 1918. Desertions and uprisings had started before the armistice. The myth was propaganda, not reality.
Bigfoot 1 in 1,000,000 No credible physical evidence, such as a body or genetic material, has ever been found for Bigfoot despite intensive searches. Hoax photos and misidentifications are more plausible than a real undiscovered ape species in North America.
Israel Blew Up USS Liberty on Purpose 1 in 50 The attack on the USS Liberty by Israeli forces during the Six-Day War has been subject to controversy and conspiracy theories. While the official Israeli explanation was that it was a case of mistaken identity, some believe it was deliberate. However, there is no definitive evidence to prove intentionality beyond doubt.
2020 Election Fraud (Trump actually won) 1 in 1,000 Extensive investigations, including by Republican-led state governments and Trump-appointed officials, found no evidence of widespread fraud that could have changed the outcome. Multiple recounts and audits confirmed the results. Courts, including those with Trump-appointed judges, dismissed over 60 lawsuits alleging fraud due to lack of evidence.
Pizzagate 1 in 1,000,000,000 This conspiracy theory has been thoroughly debunked. It originated from misinterpretations of hacked emails, with no credible evidence supporting its claims. Law enforcement investigations found no basis for the allegations. The restaurant at the center of the theory had no basement, contrary to claims. The theory led to real-world harm when an armed man fired shots in the restaurant based on these false beliefs.