Subjective vs Objective a priori probability
"What are the chances of successfully pulling off an inside job" is an example of subjective probability, not objective probability. Example:
Objective probability: It's the night before the 3rd day of the Battle of Gettysburg. Gen. Lee and his staff are relaxing, shooting craps. Gen. Pickett has the dice and his point is 10. Armistead offers Lee a 3:2 payoff if Pickett makes his point.
Longstreet advises Lee not to take it, as the odds are actually 2:1.
Subjective probability: Gen. Lee asks Longstreet what he thinks their chances are of successfully storming across 1/2 mile of open country up Cemetery Ridge in the face of of massed Union Infantry and Artillery.
Longstreet answers, "To be brutally frank, General, I think our chances are piss-poor."
Subjective probability: Bush and Cheney ask Rumsfeld what are their chances of staging 4 fake airliner hijackings, landing them at a secret airbase and murdering the passengers and crew, disposing of their bodies, and substituting specially built drone aircraft built to look like airliners, flying them into the Twin Towers exactly where demolition charges have been planted and the demolition charges surviving the impacts and fires and actually it's the demolition charges that bring down the buildings because there's no way that impact and fire could do that, and we'll plant extra demolition charges below the impact point because we're not sure that the collapse will continue all the way to the bottom but we know that flaming debris will hit WTC 7 and start fires so we've planted demolition charges there, too which will survive hours of fires and although everyone knows fire can't harm steel, we'll blame the destruction of WTC on the fires and meanwhile we'll fire a missile into the Pentagon in broad daylight in front of hundreds of witnesses we can't control and maybe some will have cameras and the missile will hit and ignite thousands of gallons of jet fuel we've stashed inside the Pentagon without anyone knowing it, creating a giant fireball, plant airliner debris around and inside the Pentagon, convincing everyone it was really an airliner, and let's also crash one in Pennsylvania just to make it look good, and nobody will suspect a thing, except for a few Conspiradroids?
Rumsfeld answers, "Are you guys high, or just out of your [expletive deleted] minds?"