It has in no way what I call a 'first class' connection to reality.
It could acquire a 'second class' (my term) connection to reality,
as people who believe it and read something good might feel
encouraged to act, and eventually something good might happen to them.
This could also work in the opposite direction, for negative anticipations.
This mechanism, of the so-called self-fulfilling prophecies appears in many other human contexts, notably in education.
All in all I think horoscope is just another witness of the strong desire we have
to find laws relating the many items of our complex our world and to deny the (depressing)
fact that bad things just happen with random causes, that is without a 'true' cause.