In free libertarian capitalists society people are mostly asset, more people means more workers and businesses and no one migrates into such society for give-outs since there are no any. In liberal socialism society people are in a big part liability and most of migrants go there for give-outs not for opportunities. So more people - more problems, not even taking into consideration cultural differences, etc.

Regrettably, there is no libertarian capitalism anymore on this planet, only several countries may be defined like that with essential assumptions. Most of developed countries are now liberal socialistic to some degree or another (give it time and they will naturally convert into less liberal forms of socialism, but that's another topic) - so migrants are a problem.

Additionally, Arabs currently are religious and cultural barbarians comparing to European population and with it's hypocritical tolerance and political correctness Europe does not stand a chance against them. They will destroy those European liberal societies. Come to think of it, it's not so bad, I'm always glad to see another false socialistic utopia failing epically and frankly, it would be much less devastating now than if it crumbles later, on more ugly stages of socialism. But if I was living in Europe and enjoyed those give-outs myself I would definitely say no to migrants.