They are there because the communist made a point of infiltrating and indoctrinating them to be there.
Read School of Darkness by Bella Dodd.
It’s on line in PDF form here http://www.americandeception.com/index.php?action=downloadpdf&photo=PDFsml_AD/The_School_Of_Darkness-Bella_V_Dodd-1963-274pgs-COM.sml.pdf
Bkmrk.