Europe didn't invite migrants because of political or economic reasons. That's just an excuse or rationale.
The real reason is that after the Holocaust and colonialism, white Europeans were brow-beaten into guilt. They were told there is nothing more evil than racism. That if they failed to embrace multi-racial, multi-ethnic, multi-religious, multi-sexual diversity, it would mean that Hitler had won after all.
Celebrate diversity or you're a Nazi. Those are the only choices.
There’s a lot to that.
“The real reason is that after the Holocaust and colonialism, white Europeans were brow-beaten into guilt.”
Agree 100%, but guilt DOES NOT directly result in a population committing cultural suicide. The guilt DROVE THEM to take political power and then to use that power to end their cultures.