That background gives him something in common with a number of other radical Jihadis, and it might be a clue to his motivation. As Passport notes:
If all this is true, it's pretty interesting. There seems to be a pattern of mediocre sons from elite families becoming terrorists. Osama bin Laden's dad was a wildly succesful contractor with close ties to Saudi royalty. Underpants bomber Umar Farouk Abdulmutallab's father was a prominent Nigerian banker and one of the wealthiest men in Africa. Perhaps they feel like failures next to their successful dads, and militancy offers a pathway toward self-respect.
I can just hear Shahzad / Fredo whining:
"It ain't the way I wanted it! I can handle things! I'm smart! Not like everybody says... like dumb... I'm smart and I want respect!"
Truly, we could all learn much about power and conflict by applying The Godfather Doctrine.
Even better, we all ought to read Eric Hoffer's classic The True Believer. Nothing is better at explaining the attraction of fanaticism for disappointed people.