Why is it that people don't accept the things that they don't understand?

There are so many things that people don't understand, so people ignore it, criticize it, beat it up. When they take a look at first glance and then try to understand it and cant find it understandable, they just don't accept it. They don't even try again. They just, blow it off like a fairytale. Because there are a LOT of things in this world that people can't explain. So does that mean we should just forget about it?