I used to have a friend abit like Sam. She never grew up in her 20s and by time she was in her late twenties/30 she was still acting like an idiot on nights out, attention seeking, having facebook drama etc.
Ended up where she had none of the friends she grew up with or had in her early- mid twenties anymore, myself included.
She ended up hanging around with 18 year olds.
Dating people a decade younger who were immature too so always ended in disaster.
Now often writes fb posts ranting about how tit her life and relationships are, wondering where it all went wrong.
Very sad.