Exception fallacy
The exception fallacy is when you use one or two unusual people or cases to say something about everyone. Outstanding or rare examples don't establish a general rule. For most people, the rule still holds—the exception is just that, an exception. Using it to argue that the rule doesn't matter is misleading. Related: Survivorship bias.
Examples
Einstein did badly at school and became a genius, so doing badly at school doesn't matter.
Bill Gates dropped out of college and became rich, so you don't need a degree.
One patient survived without treatment, so we don't need to treat this condition.
She never trained and won the race, so training isn't necessary.