Did you know, rich Arab countries don't accept the U.N. definition of a refugeee?

[Anomalocaris]

It means the victims and refugees contains a large percentage of people who, while running away today, is but one minor intellectual hurdle from being radicalized themselves.

Based on what, exactly?

Based on their own traumatic experience and, face it, the comparative lack of success of middle eastern Muslim expatriates to adapt to foreign host cultures. They can't go back home as they are, and a larger than average proportion of them won't fit in well where ever they find themselves. For many of those that won't fit in, the only solution once they discover how unsatisfactorily they would fit in would seem to be to adopt radicalism so they can vicariously go back, sort of.