One of the most important skills you can acquire in life is the ability to not trust anyone. This is very important.
You're not just born distrusting people. This is a skill that has to be cultivated over years of having various slapdicks, douches and pieces of shit do things you don't expect them to do. You don't expect them to do these things because you're naive. You're naive because you're an idiot. You're an idiot because of poor parenting. Your parenting was poor because your parents had too many kids and didn't have the time to portion out the things that needed to be taught to all of you, so you're lacking.
When you're lacking, you grow up to be fucked with. Sometimes you're fucked with by people you've known for years. When those people fuck with you, you begin to acquire the "skill" of not trusting people. That's when things get fun.
When you don't trust anyone, your relationships all turn nice and dysfunctional. You don't believe anything anyone tells you, because you think everyone else is going to turn around and do the same thing the aforementioned slapdicks, douches and pieces of shit did. You're gun shy, and you're angry, and you say and do things designed specifically to prevent yourself from being fucked with again.
The best part is when it all plays out in your mind, over and over again, until the wee hours of the fucking morning. You learn another skill. You learn to be an insomniac. You learn to read and watch CSI reruns and fuck around on the computer until four in the morning, even though you know you have to be at work in a few hours. It's an amazing feeling. A rush, even. It keeps coming back to you again and again, and all you want to do is go out and not trust everyone you see, because you think everyone is a slapdick, a douche and a piece of shit.
Actually, I was wrong about the best part. The best part - the pinnacle of it all - is when the world acts as though you're immature for wanting a little payback. They act as though you're supposed to swallow it all. They tell you to shut the fuck up and stop dwelling on the negative, because it's "hurting your progress" and "keeping you from being happy," when all you want to do is have someone pay the check for the meal that was eaten at your expense.
These are important things for you to know.