Once I began to understand the key dynamics in radicalization, essentially, poverty, "romanticism" resentment, you can see that this isn't going anywhere, and that our current leaders will only fuel these kind of attacks. The same reason kids in Juarez, Tijuana, wherever, get recruited as killers and assassins and kids in Southeast San Diego, and across the nation join gangs, they aren't all exactly the same thing, at all, but the causes mostly are. You sell people with nothing, few options, little education (in many cases, not all) the chance to die for something. You sell them a team, a vision, a side in the war of good vs evil. Calling them losers on twitter is such a fundamental misunderstanding of the problem. They know they are losers, that's why this happens. Society is already telling them that. Why be a part time security guard, a loser, when you can die a martyr? Why drive a cab, and be berated and insulted by white tourists when you can die for what you believe in?
And the clown in this thread, ranting and raving is the worst part of the problem, relatively speaking. The moderate muslims....where are they? All over, watching this horrific attack with the same anger, sadness, and added fear that this will further their persecution in the West.
Also, whether or not they were refugees, isn't relevant. You can't close out the kind of issues that are causing this with walls, or bans, in Western countries. Maybe this person was a refugee, the next one will be a citizen.