>>514771736 (OP)
Not exactly hard to picture: person already lacking in social skills finds it easier to just put a wall between himself and the world after being burned one too many times by his failure to fit in, and the modern world allows this lifestyle to be feasible without starving to death, thus it prolongs indefinetely.
Whatever the specific are, if the person gets no joy but lots of pain from engaging from society, then it's gonna be damn hard to get them out of their lonely but comfortable cave. What are you gonna do, shame them to come out? Shame is precisely the reason they're inside in the first place.