At this point it isn’t so much about the European mega-state anymore; it is about Europeans tired of watching their countries fill with foreigners, and their elected governments hiding behind the mega-state as the cause of it.
It was very telling when over the past year there were several analyses of the leaders of Western Europe - and how many were childless. There is no future for them personally, so the long-term effects of these policies mean nothing. In fact, they are protected from the immediate effects as well behind their walls...
Immigrants are welcome because they help to undermine national identify and integrity. They aren’t committed to the national states, vote left and they are heavily dependent on social benefits. They have low IQ and lack of perspective to make any progress. Neo-Marxist elite sees them very helpful in process of creation of one European state. Immigration is just a tool, definitely not the goal.