They have something to worry about because they arrived as children having not being born in the USA.  That is the essence of the issue.

And an inhumane and cruel policy would be to take grown adults who have only known their life as a someone who has lived in the US, who has followed all the rules, who has been a contributing member of society, and who has established relationships and send them back to a country for which they are unfamiliar with no community or social ties.  

All because a political leader wants to score points with his base of support.  That is the not the America that I know, an America that is compassionate, open, and caring.  An America that leads the world (before Trump) in giving, providing opportunities, and welcoming to strangers.  It is so sad to see a great country reduced to being a laughing stock run by a man consumed with self interest, greed, and cruelty.