11/30/14 How Much Are We Supposed To Care?

We have been fortunate to have some extra income which has allowed us to be generous and helpful to many of my older son's friends.  We had one move basically move in during first grade.  He was with us all the time, his parents going through a divorce.  We loved the boy, but in ninth grade, his mom decided Catholic school would be better for him, and then we moved across town, slowly he has disappeared, which I understand.  He does converse with us from time to time on FB, but we are no longer close.
  Then there was his other friend, who also had parents divorcing somewhere in third or fourth grade.  This was a wilder child, and he would try to be a smart ass to me behind my back, but I believe with my guidance this boy at least turned out civil.  He hung with us until graduation day from high school.  It was weird, he said thanks for everything and mostly stopped visiting us.  We've talked to him here and there but he hasn't come over in about three years, who knows.
  In high school, my son befriended our biggest challenge.  One of his friends was "kicked out" of his house and this kid moved in with us.  It started with sleeping over two and three nights in a row, then I'd say go home.  He'd leave for a couple days but come back.  Eventually, my son explained what was happening at his house and I said Ok, he can stay, but I don't want bullshit, he is going to fall in line and go to school and help out.  Kid seemed appreciative in beginning, but it wasn't a month before he started having psychotic episodes.  My wife having access to support centers took him to get evaluated and he was put on a couple meds.  The rest of the school year was rougher than it had to be, but I felt bad about kicking him out, so he stayed until the end of the school year when he directly challenged me.  I had given him some money to take his girlfriend out to the movies and then a couple days later told him, hey cut the grass, he said "no, I don't like the way you talk to me".  I swear I treated him the same I do my own boys.  This was the end, he moved out and peace was restored to our household.
  Now in college, those issues seem to have stopped, there was a last hanger on, one of our old neighbor's nieces also was close to us spending most summer days with us it seemed, even going once with us to our hometown when she was in fourth or fifth grade.  We loved this girl as our own for a time, upon graduation from high school, she declared she wanted to succeed and I felt she told me directly to help keep her in line.  I have tried, explaining to her that college demands sacrifice, when friends seem to be partying, you must have the strength of character to do the responsible thing.  This worked for a while, but being ditzy and hot, it was going to be hard to stay focused on books.  I almost feel like I let her down, but in reality, it was her refusal to stay on task.  Guidance can only take you so far, one must have their own internal fire to push you and help you succeed.
  So here I sit now, these kids are pretty much done with us, I tried to at least provide an additional layer of protection and support, maybe it helped, may it was a waste of my money, who knows.  My boys are good either way, my older one is in his third year at a university, studying physics and chemistry, while my younger one doesn't seem to attract the "needy ones" so we aren't raising other people's kids currently.  I will say that I loved these kids while they were with us and it does hurt a bit to let them go, but they can always come back, I tell all of them, my door is always open.