I've been around the mass immigration and mass illegal in-migration debates long enough to have heard one particularly eccentric open-borders argument boringly repeated time and time again, each time as if it is sure to have a devastating impact:
"Just like what you/we did to the Indians!"
A few humble points:
(1) The Europeans who arrived in what was to become America were not actually immigrants. You can call them explorers, colonists, pioneers, settlers or, if you'd like, invaders and conquerors. But they were not legally or illegally immigrating into a legal state or nation, since there were none existing in the legal sense that would have been able to recognize and declare people as legal or illegal to their immigration system.
(2) And isn't it curious that many of the same people who are endlessly piously telling the rest of us to joyously "Celebrate [ever more] Diversity!" that is being brought about by mass in-migration will then often turn on a dime and argue that European Americans should keep their mouths shut because they did the same thing to the Indians? So which is it? Do we celebrate diversity or do we get ready to have our civilization put to sleep? By this logic, when American Indians were losing their territories one-by-one they should have been having one heck of a long loud huge thankful Katy-bar-the-door celebratory Mardi Gras.
(3) Still not strange enough for you? Try this one. Those making this "Just like you/we did" argument are obviously presenting themselves as being friends and sympathizers of the American Indians, but how in the world will the remaining Indians (according to the U.S. Census Bureau, about 5.1 million, counting Alaska and including those of mixed race) benefit from being ever-more inundated by outsiders from almost 200 other nations? And what is even worse for Indians is that modern newcomers and their offspring will likely feel little or no obligation to treat Indians with at least a little more respect for past wrongs done to their ancestors by European settlers, as far as having special 'nation' status, casino monopolies and the like, since most modern newcomers and offspring will have zero past family connections to European settlers.
So what to make of this bizarrely contorted open-borders thought process? Here's a big clue. Just take a look at Europe, where white people have lived for thousands of years. Is the Left and its friends saying to Europeans, "Since you did not take your land away from the Indians, you have every right to regulate immigration and illegal in-migration as you wish." Of course not. They are just as vehemently arguing for open borders in Europe as they are in the United States. Obviously American Indians are just one more group of people that open-borders propagandists are merrily trampling underfoot to reach their goal.