Who knows. But I know this: hatred, pure hatred, is like a virus. Some people just hate others-- some for different reasons but the main reasons are because of differences- either ideological or physical (race-gender) or because one group feels oppressed by another.
Not to go off on a diatribe that will launch people off on tangents-- but years ago I read on book by Simon Reeve called "the new jackals"(1998 I think). He warned about the new faces in terrorism- mainly Ramsey Yousef and Bin Laden.
He referenced a meeting between bin Laden and Peter Bergen where bin Laden laid out three reasons why they declared war on America.
1. We had boots on the ground in their holy lands of mecca and Medina.
2. We were allowing the Saudi royal family to remain in power by purchasing the oil that rightfully belonged to the people- not the royals.
3. We were giving billions annually to Israel in weapons and money.
Stop doing these 3 things, and Bin Laden would call off the dogs.
Well, we didn't-- so it began. Now it has spun out of control. Say what you want about bin Laden, but he wanted his attacks to be focused more on "political and financial symbolic targets"-- those were his principals (for lack of a better word).
These new cats-- they don't care. There are no rules. No principals. That Micheal Cain line from batman-- "some people just want to watch the world burn" really suits many of these people.
As far as "what do we do"? Well Bell, given what I just read from the 9-11 report that shows WITHOUT A DOUBT- that Prince Bandar of Saud was directly paying money to many of the 9-11 hijackers, and providing them with saudi military and intelligence contacts- I say step one is cut off all ties with the Kingdom of Saud. Never by another drop of oil from them. Ever. Without our financial support, they will wither and die on the vine.
2nd- strengthen eastern Eurasia with NATO troops in order to keep the bad people in that area-- IN that AREA. They have a blood feud that won't involve us, once we leave, and they've had that blood feud for a millineum. Let them sort it out.
3rd- instead of spending 8 billion annually on Afghanistan, 9 billion on Iraq and God knows how much on the rest of the middle east, use that money to properly protect OUR country and our western allies. Protect the homeland or the cancer will spread. We need to form a thorough vetting system in order to help those people that "truly need our help" and are committed to coming to America and adopting OUR laws while becoming a contributing member of US society. Holding dear to some of their culture is important, but not at the expense of violating the laws of the US or suppressing the freedoms of our society.
We can learn to coexist with people that make an effort to respect our laws while living in our country. The rest of them either need to return to their homeland and fight for it, or if they are committed to terroristic acts, need to die. Period.