By the same logic, nationals of these other countries have no right to our collective lands either. They belong to us exclusively to do with as we please. Open borders represent the immediate loss of territorial ownership by the nationals living within them. Having an open border where anyone can walk right in and live within that country is like having one's front door removed from one's home and allowing strangers to just come into the house, lie down and sleep in the bedroom, and take possession of it which violates the rights of the owner. The door of the home is there not only for protection, but as a sign that this property is not to be entered and that it is spoken for.
Borders are doors, also.
People should respect them, especially foreign people, and not try to take from others what is not theirs.