The investment thing is certainly true. There is an expectation that the children will keep (or at least subsidise) the father as soon as they start to earn. There is a pecking order where the oldest son contributes almost all of his earnings to the father and younger children, then when the younger brothers start to work they also subsidise the father, but free the older brother of his responsibility to them. Back in Afghanistan the family of my boys was considered to be 'wealthy', but it seems that it's all about ostentation - being 'seen' to be able to afford things. So you may not eat well for a month (unseen) in order to buy the latest TV and impress the people around you with your 'wealth'. So when the boys first arrived they were shocked that we drive an old car (and share even that) and don't have TV's in every room or the latest technology. They constantly asked why we didn't buy particular things and were initially fairly shocked that we considered relationships to be far more important than 'stuff'. They talk about 'family' as being very important, but are grossly ignorant of family matters such as family history, how parents/grandparents are employed or family relationships. They also have little contact with family except for practical matters and the concept of a family discussion was completely alien to them.
In view of their lack of closeness to relatives I had wondered if we would see much of them now that they've moved on, but I've already had a text from the youngest asking if he can call in tomorrow.