Well, Americans aren’t reproducing — haven’t been for decades. Especially college-educated Americans.
This has economic and fiscal consequences: lack of future workers and consumers. Lack of taxpayers. Aging population consuming more than it produces.
So what do you expect?
No offense, but that's a patently false assumption which is used by the globalist elite to justify overrunning the West with third world barbarian invaders.
America's native population has continually grown, even without the help of immigration. Maybe not to the numbers it did in earlier centuries, but it has nonetheless continued to grow.