Muslims themselves can never solve this problem on their own. A lot of the guys who do this stuff have left mosque congregations because they were too moderate for them. Many of them become radicalized online without their parents or communities knowing. In some cases, the parents might be a bit relieved because their kids start taking a bit more interest in religion and not getting into so much trouble with petty crime. It seems pretty common for these guys to evolve from criminal activity to this uber violence.