> 9/11 happened because someone outside the government planned it and it didn't need that many to work. If the US government was behind it the way the conspiracy theories are told, it would have had to involve tens of thousands of people.
Would it?
First off - I don't believe the evidence supports the US government doing it. I'm not saying there aren't any unanswered or uninvestigated questions, only that the evidence we do have and has been investigated doesn't support it being an "inside job". That said...
Why couldn't Bin Laden have been supplied money and plans via say the CIA or something? Obviously covertly, in such a manner that Bin Laden wasn't aware that this was being done on the behest of the CIA. If the money and such were coming from some black-ops line item in the budget, and things were kept extremely tight inside the government agency and abroad, I honestly don't think 10000+ people would be in the know, or need to be used. It could probably be done with fewer than 100 people, and if those 100 people were dedicated enough, they would likely all keep mum about it, especially if the plan succeeded.
Basically, I'm postulating on the fictional idea that there could be a group of people, high up in a government or other quasi-government agency, who are (in effect) led and acting on a hardcore fundamentalist belief system that says that (for whatever reason) the US needs to experience this attack and for it to happen in such a manner to change things. Essentially, an inside rogue terrorist cell. Perhaps it was built up over the decades since the Reagan years (or even further back), with the idea that once large enough, the plan would be carried out in such a way to not implicate them, and ultimately install their guy at the top. Kinda a slow-mo coup or something, with the attack being the illegal precursor to the takeover via legal means (because of terror and fear pushing people to vote in a much different manner - perhaps manipulated as well).
Probable? Not likely, outside of Tom Clancy novel. Possible? Well - perhaps. We've learned of stranger things in history, long after the events have passed.
Ultimately, there's no evidence for any of this being the case, and it's just a fictional possibility. But I don't think it is something that would require 10000+ people to pull off; that's only necessary if the group doing the work needs it done "now" - and isn't willing to wait decades for the final shoe to drop.