I mean are we a mistake? That's extremely subjective to say and I would call such labeling a cognitive dissonance. We just are... different than other people which doesn't make us a mistake. Some people are bipolar, autistic, suicidal but also "smaller" things like being left handed and such. Maybe this universe is a mistake and not we? Maybe the society is a mistake but not we? You can call everything a mistake but does it actually help you? We weren't born to fail, there are numbers of stutterers which are succesful. Your brain is just picking up a negative way to look at the world. Sure I won't deny there are numbers of stutterers whose life is least to say horrible, painful. But why do you only look at them and not the succesful ones? If you truly believe that you were born to fail then well, you are probably going to fail.