It's easy to do. To take a few instances and make it a universal truth.
I've been getting posts about this in my Facebook feed. These pictures show lies, so therefore everything in your life is a lie. It's an easy trap to fall into.
Just because that one guy was a jerk doesn't mean all guys are jerks.
Just because one person got hurt on that ride doesn't mean everyone will get hurt.
Just because your team lost when you watched the game doesn't mean you have to not watch any for them to win.
Just because you had a bad day when it rained doesn't mean every rainy day is going to be a bad day.
You get the picture. Learn to separate a single truth from a universal truth. It will make life much better.