This person started working for a large retailer. On their first week, they contributed a fix to a filtering system that inadvertently disabled the "adult" filter.
The team got paged, an error review took place, and we went through the impact of the error - a ~10% increase in sales worldwide, and the best sales outside of the holiday period.
On one hand, extremely damaging for the company. On the other, on his first week he delivered impact that exceeded the whole team's goal for the year.
That person is now in senior management at a huge tech company.