People allways need hope when things go bad. With hope, they expect to find force into them until things go better.

Astrologists are hope sellers. Their information is profitable temporarily for the customer who pay. "Profitable" because customers buy hope which will help him to pass time during difficulties.

Then, when the short time passed, 2 issues may come :
Either things go better, so customer will say the astrologist was very wise,
or things remain same, so customer will say the astrologist was wrong (but maybe temporily ? God knows..).

In both cases, he was right or wrong, astrologist made his work : Selling hope and bringing temporarily comfort into his customers' believes.

Horoscope is above all a business of "selling hope" even before being a business "for reaching the truth". But this, people refuse to see it, because if they realise it, they would no more be able to buy hope and find comfort by this easy way for the coming period of uncertainty.