Zodiac signs don't determine whether someone will gamble or not, your personality, environment, upbringing and exposure do. it is easy to see patterns when you want to. For example, you notice your Aries and Gemini friens are impulsive gamblers and it fits what astrology says, but thats just confirmation bias, you notice the cases that fit the theory and ignore the ones that don't. Your Virgo friend is a perfect counterexample and there are plenty of Aries or Geminis who never gamble.

Gambing tendencies are shaped by risk appetite, peer influence, financial habits and self-control, not stars in the sky. Astrology may feel like it explains behaviors because we humans love stories and patterns but there is absolutely no scientific link between a birth date and the likelihood of gambling. I will add this though, if someone uses astrology to self-reflect on their habits and triggers, it can be harmless tool for self-awareness, but it should never be treated as a predictive tool.