Why were the stalkers in the movie?

I think it was just a gimmick to sell this as a horror film and to provide some cheap scares, or at least try to. This is a film about an accident victim's thoughts while she decides whether it's worth living when her friends have died, and perhaps those stalkers represented the battles she deals with guilt and recovery. But for me, those and other gimmicks spoiled what could have been a very touching film.