Europe has, so far, dealt with low-IQ Muslims who have managed to kill a few people in one attack. Sometimes, dozens if they're "lucky".
But what happens when a genius-level Muslim decides to go full Jihad? A biological, chemical or nuclear attack could easily wipe out millions of people in a few hours. A dirty bomb could leave an entire country devastated for centuries. Out of, let's say, ten million Muslims in Europe, only one piece of shit is sufficient to cause such death and carnage.
This is why dumb statistics don't make sense when we look at the dangers of Muslim mass migration. More people die from drowning in their swimming pools than from terrorist attacks. So what? That drowning rate is basically stable from year-to-year. The terrifying probability of a 9/11 or worse is not constant! The fact that civilians in Europe have never been on the receiving end of a nuke tells us nothing about that possibility in the next week, month, year or decade. To dismiss such an event is to be colossally blind to the evil of Islam and its adherents.