They have aborted, birth controlled, and homosexualized themselves into demographic oblivion, and millions of them can't muster the energy to resist--or even to reproduce.
Europe has been trying to commit suicide for centuries. Maybe now they'll succeed.
In a certain way, they have had it too good for too long. The survival instinct and national pride has been bred out of them.
In centuries past, war and pestilence served to keep things going as terrible as it is.