Does anybody worry about becoming a ghost? I mean, assuming a hypothetical belief in them in the first place.
I think it's strange that we see no sign that people who believe in ghosts worry about becoming one, because it seems to be the obvious question: is this my future? Often, becoming a ghost is seen as a punishment for evil acts in life, or the consequence of them. Matthew could have old ghost stories going through his head right now, where evil people are never allowed to rest, just as he's getting ready to kill someone himself. This could be a large part of why Matthew is so disturbed by seeing proof of ghosts.
Maybe no one worries about becoming a ghost, but if ghosts were proven to be real, I think a person would have to be a fool not to start worrying.