I'm not sure what the quote at the URL says, as it goes on several pages and I haven't looked at them all. But the point is that there is no "them" as such. Al Qaeda is not a body of men, or a nation state, or any collection of these. There is no organisation called "Al-Qaeda", despite what Bush/Blair and other shallow politicians say. It is an idea, an ideal, rather like a religion, and as such it's very hard to counter. Rather like Christianity, where they say you must have "faith" without seeking any intellectual support for that faith - the more it's attacked, the stronger the motivation for the "faith". The author does suggest hatred of the west may be borne from envy, but in itself that's also way too simplistic.

You really do need to read the book, as the subject is very complex. To encourage you, look at the Amazon.com website for the book and read some of the comments about it. It isn't "just another book" written by someone who thinks he understands what's going on, but an erudite and very well researched and cross referenced study by someone who has been closely involved in the area for many years. Please don't ask me to give a slick answer to what an expert struggles to cover in a lengthy book - I can't do it and I won't try.