Those that I've known that use Horoscopes do it for fun, akin to
  fortune cookies, a wistful "what if" but don't take it entirely
  seriously. It's used as a categorization akin to personality
  tests without the tests and, I believe it's mostly harmless in
  the common use.

  Of course then there are nutters.

  I always had a fondness for biorhythm charts. They're not true
  but it's occasionally fun to look up one's biorhythm chart for a
  particular day.*

  Good for amusement value [because where else can you be told
  _something_ about your life based upon when you are born and
  what day it is] but woe to anyone using as a way to guide their
  life.

  Then again, some people believe economics pundits and use them
  as a guide to investing. Silly people.