There are various reasons why we are so hated by a terrorist faction within Islam. This simple essay brings together the history of events that helped trigger off such violent hatred.

I read that and also watched this video documentary, the History of Oil, and with a bit of reading in between the lines, we can't deny we know exactly why they are shooting us down.

The big change happened here:

But in 1990, Iraq (led by Saddam Hussein) invaded Kuwait. Fearing that Iraq would next invade Saudi Arabia, Bin Laden offered to bring mujahedeen from Afghanistan to Saudi Arabia to help defend it from attack. Instead, Saudi King Fahd decided to rely on American military forces to defeat Iraq, and he allowed them to set up bases in the Muslim holy land.

The stationing of non-Muslim troops on Saudi Arabia’s holy soil transformed Bin Laden. He viewed King Fahd as a traitor against Islam. From this point, Bin Laden became an outspoken enemy of the Saudi ruling family and its American defenders.

http://www.crf-usa.org/america-responds-to-terrorism/islamist-terrorism-from-1945-to-the-death-of-osama-bin-laden.html

History of Oil - part 1 to 5