You could easily be forgiven for not knowing about the part of history where The Plan of San Diego threatened the United States:
Some radical elements saw the Mexican Revolution as an opportunity to bring about drastic political and economic changes in South Texas. The most extreme example of this was a movement supporting the “Plan of San Diego,” a revolutionary manifesto supposedly written and signed at the South Texas town of San Diego on January 6, 1915. The plan, actually drafted in a jail in Monterrey, Nuevo León, provided for the formation of a “Liberating Army of Races and Peoples,” to be made up of Mexican Americans, African Americans, and Japanese, to “free” the states of Texas, New Mexico, Arizona, California, and Colorado from United States control. The liberated states would be organized into an independent republic, which might later seek annexation to Mexico. There would be a no-quarter race war, with summary execution of all White males over the age of sixteen.
As usual, one Leftist success begets others. When the Soviets were part of the victorious alliance in WW2, it became official knowledge that Leftism was the path forward, and even capitalist societies competed for socialist achievements.
This brought us to the civil rights era where any privilege not extended to everyone was quickly obliterated, doing away with culture and hierarchy, then following it up with population erasure through diversity.
On the heels of those victories, the Left wants to push a Plan of San Diego for all of America and Europe: third world races will replace the indigenous first world peoples, obliterating the Cro-Magnid race.
A realistic view of history shows that every population will attempt this kind of conquest unless held in check or wise enough to make itself entirely self-sufficient, content to let the rest of the world seek its own doom separately.
Humanity has clearly taken leave of its senses if it considers diversity to be anything but a prelude to this kind of genocidal race war, since history shows us that diverse populations give rise to constant ethnic conflict.