Yes, addiction has a physiological component in many cases...but people who are happy and fulfilled in their lives have a much, much easier time quitting highly addictive drugs than people who are poor, lonely, and disconnected.
Much of the Foxtrot Gang is associated with the PUK as much of the Kurdish community in Scandinavia is Sorani (Kirkuk-Sulaymaniyah-Kermanshah)
The issue is, vetting is hard and most countries suck at doing background checks due to a lack of staff.
Denmark has no more room in its prisons. Opinions are shifting away from importing infinity third world migrants, and news media is now allowed to talk about it, but not enough to meaningfully shift votes in the last election, so it's going to be more of this for the forseeable future.