Jihadism provides these youth a sense of purpose. We failed at this. Now they fight for what is sold to them as (and they firmly believe to be) a high spiritual purpose instead of doing the jobs nobody wants to do and living a dull life in poor suburbs being treated like shit while watching rich white people enjoy loads of money on TV. In essence.
Your argument smells a lot like the self-made-man American myth. Just because some have made it out of poverty, often in different conditions than these, doesn't mean we don't have to fight poverty because everyone who is smart enough will pull herself out of it by her bootstraps (and I'm not talking just about material poverty).
Shouldn't be in the interest of the majority to make sure that minorities are not marginalized?
Imagine if 25% of American kids said they could relate to the Sandy Hook shooter, wouldn't that be worrying? Regardless of whether they'd be out to kill as well.
On the other hand I would like to see this study that shows that increase in the level of education and occupation doesn't do much. I suspect the issue is more subtle: in that many immigrants coming from the former colonies of France don't really identify as French (even after a couple generations) and don't fully accept the so-called 'republican values'.
The fact that many of Portuguese origin are converting to radical Islam seems to me as a further symptom that the power of Jihadism actually stems from socio-economical marginalization.