Suppose you live next door to a jerk.
And suppose the jerk though you were a jerk.
And suppose you were both right.
You bickered and swore to burn each other’s house to the ground.
And you would have, except your daughter fell in love with the jerk’s son. And miracle of miracles they had an adorable child.
Would you set the house of the jerk on fire and take a chance on killing your adorable grandchild?
Probably not.
Now substitute any country for your house. And any country for your neighbor’s house.
See what I’m getting at with immigration?