You are realistic, and realize that impossible does not exist. It is an oxymoron. Nothing is impossible. They on the other hand, are not realistic, and so will never achieve that which seems impossible right now.
yo dude it is awesome to be unrealistic (in situations that you don't need to be) i dream about giant dragons and amazing stuff like that. Just because i dream fantastical doesn't mean that it is bad to. You are being realistic it is just that what to you is realistic to them is fantastical