In the book, he says 'what went wrong' was, they became religious fanatics. If you 'worshiped' science, over Mohamed, you were to be killed. They view any 'modern' thoughts (medicine, engineering, education, personal wealth, etc.) as a slap in the face to their prophet, Mohamed.

You don't need to get an education, or get a job, or try to better your life, you only need to worship Mohamed...

And if you DO try to better yourself, you must be an Infidel!

Because you should be worshiping Mohamed, not getting an education.