What reason do they have to attack us at home?

From what I have read and heard is that Bin Laden hated us for having troops in Saudi Arabia, not because they hated our culture. He has said they are intent on an islamic World from Spain to the Middle east, were we are not involved. If we just get the hell out of Iraq and the middle east in general (including support for Israel) it seems it will make us a much safer country. We should buy our oil and be done with that hellish place, it is not our problem if they want to kill eachother.