We've all gone through life thinking we're fuck ups, and you know what?
We are. All of us. Some of us achieve in spite of those fuck ups and some of us achieve because we're just goddamn lucky. Most people achieve what they achieve because they find something they're good at and stick with it.
Don't hold yourself up to the most beautiful mirror you can find. Instead, gaze into the pond that is life, and you'll find your reflection is more than adequate.