Is What my Friend doing wrong for her age?

My Friend is 16 years old and is sucking on a pacifier. Her mother was neglectful of her needs when she was a newborn, and she was placed in foster care. She spent 10 years jumping from home to home before returning to her original house. She pretty much runs the family. Her father died when she was a newborn and her mother is kind of hapless and needy. I think she sucks on a pacifier to live some of the life she was never able to experience as a child. Do you think this is appropriate?