And suppose that just before he is born, his parent rob a bank for millions of dollars. He grows up in wealth and style. Should he be "punished" by the loss of his lavish lifestyle when when his parents are finally caught and the money is recovered?
The problem is that the parents can't be deported because it would separate the family and he must be provided with government benefits because he is a citizen. Fix those problems and I have no problem with making him a citizen at 18 or 21.
His family is also exploiting him. He’s being used to get checks and benefits that should go to him alone. but they are mooching off of him, including his extended family that decides to go along for the ride.