I don't believe in astrology either, but frankly, this sort of zealous hyper-rationality is a great way to die alone. Like someone who's not into astrology will overhear you and the word that will get around will be "Don't invite that guy to parties, he is not fun." You will reap far better dividends from just taking people as they are and trying to find the best in them. Which is the most rational thing to do is it not?