This reminded me of the article "The Jihad Cult: Why Young Germans Are Answering Call to Holy War" [1] - after reading it, I got the impression that at least some young men became jihadists because they are basically narcissistic losers whose attempts to be cool via normal and non-destructive means (like becaming famous rapper or kickboxer) failed so they convinced themselves that joining ISIS is the cool thing - they perceive it like courageously fighting with their 'brothers' to enforce God's will... or something like that, they perceive this concept as cool and some of them desperately want back home when they get to Syria and see the grim reality of real ISIS. The whole article is worth reading.
Post-modern Western journalists and politicians are spectacularly ill-equipped to understand and hence deal with, people who actually believe in something, whatever that thing may be.
Any sort of Group of people X is Y statement is very unlikely to be true, but this is more so than most. Western Journalists regularly risk life and limb for what they believe in. In many ways it's like saying the clergy are atheists sure some of them are, but there is strong !atheist selection pressure going on.
It may also be just a piece of propaganda, especially since it's written by Spiegel.
Somehow all opponents to the pro-US mainstream opinion end up there being narcissists (IS), evil dictators (Putin, Assad) and weak governments (Iraq, Afghanistan, just recently Greece), usually ridiculing them without asking for their motives.
A few months ago Spiegel even had to defend itself openly because people cancelled their subscriptions due to what was perceived as warmongering (Kriegshetze)
My own opinion is that unless media reports positive and negative aspects from both parties (because there is never only one culprit, neither in politics nor in marriage), they cannot be taken seriously.
I predict this might give me a lot of hate, but these people coming back is the worst possible outcome for (not only german) society. I don't believe for a second that at least most of them are not properly unbalanced (or worse) and will do no good to society for rest of their lives. I cannot imagine myself doing something like that, and I was no angel when teen. You can see in all media how war looks like there, so they cannot say they simply didn't know.
They wanted war, let them have it all the way to the bottom with all the (percieved) glory of death. They had chance offered to become members of society they were living in, and they refused. Okay, we should respect that choice, but with all consequences. Younger age is no excuse for such mistakes.
[1] http://www.spiegel.de/international/world/why-young-germany-...