People living and working there? Paying taxes? Being doctors or teachers or garbage men or kebab place owners? Is that not a contribution? I live in Antwerp, in between a whole lot of muslims, and the vast majority of them is friendly and law abiding, exactly like the vast majority of non-muslims. Some people on the other hand, are assholes, but you'll always have a couple of those.
Everyone just needs to chill out a bit and look at the problems ahead. The rise of extreme right nationalism in Europe is far more concerning than a couple of desert dwellers in Syria and Iraq planning their next attack. Last time it happened, it meant war and genocide. Tell me I'm exaggerating, but when a bunch of bald dudes proudly start doing the hitler salute again, and when condemned racists lead the polls in France and Holland for example, that ACTUALLY worries me. All of that jihadi shit in Europe combined makes for less casualties than one year on the Belgian highway.