In case of youth: Because they might dislike the good words that usually tell by the old people. If they were young, the old people will teach them how to be good, how do we have to do work and they try to motivate them which the most of the young people would not try to hear.
In case of familes: And mostly now a days, Many families are in a thought that the elder people are just became burden to them which leads to send them to the orphanages etc.
These all are happening due to the blocking of the site of humanity in our minds. So be aware and open your minds broadly..