Where someone chooses to live is irrelivent for a variety of reasons.
Several people that I know, myself included, choose to live w/parents to take care of them as they get older. Honestly, for someone who works near their parents and is not tied down w/kids or a marriage, I think it’s the right thing to do.
Or how about a young adult with healthy parents? Maybe they are saving as much money as possible for a down payment on a house, etc.
Yes, I realize that some young people are forced to live at home due to lack of income and/or poor spending habits, but it’s not always the case.