Consider two statements:
A) Most immigrant graduates are of low caliber.
B) Most immigrants of high caliber have graduate degrees.
In my experience, both statements are true.
Disclosure: Immigrant, hiring manager at reputed SV company, with UG degree from my home country.
Citation needed.
In any case, here you go: https://www.dhs.gov/sites/default/files/publications/Unautho...
You then come back with an article titled "Estimates of the Unauthorized Immigrant Population Residing in the United States: January 2014", when the discussion here is about students gaming legal immigration. What relevance does that have to the topic, again?
Its pretty clear that you've made up your mind about what the state of the world is (from various anecdata) and don't really care what the statistics really say. I will leave this as my last comment about this issue.
[1] https://www.mercurynews.com/2011/01/20/tri-valley-university...