Why are Scorpios always doubting everyone?

Most Scorpios I know are so weary of everything and everyone around them. They hold on to the past and remain bitter from bad experiences. When they meet me they wander how I could be so open with my heart and I tell them life is too short to be so bitter! In the end were all going to die! lmao Anyhow..people say Leo and Scorpio are alike except Leo is extroverted and Scorpio introverted....both are the most ual signs of the zodiac!