Hear me out: if someone believes in horoscopes, they know what each sign mean. Which means they recognise themselves into a sign. Which means they will mostly act in ways to conform to that sign, giving you a way to figure that person out. The sign tells it all, it’s a self-fulfilling prophecy.
No it’s not …
OP is saying understanding star signs influences someone’s behavior.
They’re not saying you can tell someone is an idiot because they believe in star signs.