Inside job? No

Did certain people including the government have knowledge of it ahead of time and worked to exploit it? Yes

Did certain groups even maybe coerce the terrorists into flying the planes into the buildings? Very possibly.

But end of the day I believe it genuinely was terrorists angry at America who wanted vengeance, but I also think we definitely could have stopped it ahead of time but they (mostly Jews) were willing to let people die as an excuse to start a war.