Biden explained the entire point of mass immigration back in 2015, when he was Vice President:
"An unrelenting stream of immigration. Nonstop, nonstop. Folks like me who are Caucasian, of European descent, for the first time in 2017 we'll be an absolute minority in the United States of America. Absolute minority. Fewer than 50% of the people in America from then and on will be white European stock. That's not a bad thing. That’s a source of our strength."
https://sports.yahoo.com/news/biden-wave-immigration-not-going-stop-video-135620136.html