When one worker writes a code that drastically improves his factory's efficiency, his bosses don't realize that if he goes, so does the code. 

While working for a "plant based company," one factory worker realized he could make everybody's life easier by writing a code that automatically registers when a machine stops working; instead of manually reporting the issues as they had been doing. Fast forward a few years and new management decided to make a large portion of the workforce redundant. Unfortunately for them, that also meant eliminating the man responsible for taking care of the code that helped them report mechanical issues. 

But despite the employee warning them of the problems his impending termination might bring about, the company decided against buying the code off of him. Predictably, a few weeks after leaving, the worker got a call from management to come back or train someone to maintain the code. Instead, the worker decided to show them the same compassion they showed him and denied all requests. Someone else was going to have to solve their problems. 

Ultimately, the employee sold a new version of his code to a new company and began working there. The moral of the story? Don't fire the dude maintaining your company's essential code.