If colonialism was a great thing then mass immigration is a good thing.

Western Countries are struggling with low birth rates and finding anyone who's willing to work. Mass Immigration is the solution to the failure of Western Countries.

Why is it ok for Europeans to do colonialism on brown countries but it's not ok when brown countries do colonialism on Western Countries?

Isn't this a bit hypothetical?

Without responding emotionally or being racist. Explain to me why you believe white people shouldn't be replaced in western countries? After all of the centuries of colonialism, genocide, wars, and slavery committed by whites.

Why do you care if white people are becoming mixed with browns or becoming a minority?