Yes, you can't prevent all stuff. In order to do that you'd need to basically, sort everybody out, to get everybody to be right in the head... Which will never happen. Or at least not in the next few centuries. :) But I think we could make it harder for crime to happen.
Regarding the comment of Invicta, I won't go into personal details because I find it to low and to pathetic to bring that up in an argument with a third person which has nothing to do with that. The fact that Invicta does it just shows the level of his frustration and the lack of his arguments for a fact. And the fact that he actually tries to ruin a conversation I have with a third person is as desperate as it gets.
And I don't need to say anything, he said it: 'Drogash is a muslim student living abroad... everything's America's fault', so, if I'd be a muslim, that would be enough of a reason for me to be wrong and for my attitudes to be completely implausible and malicious. A pure example of chauvinism, ignorance and a totalitarian mentality. Enough for anyone with enough intellectual capacity to understand what's it about.