Company was founded by "visionary" CEO that is an sculptor and doesn't understand tech.
Most crucial employee is young guy hired right out of college.
Company now has 50+ developers, but the critical software is still made by that guy several years later.
Critical guy still get recent graduate salary, notices he is actually the most important person in the company, and asks for a raise.
Company denies his raise. He quits. Company hire a bunch of developers from cheap third world countries to replace him...
Company learns: 1. All software guy made a bit before he asked for a raise was on his personal, not company github. 2. The software is in other programming languages, not the one the company uses normally. 3. Everything the guy wrote since he joined the company, is extremely difficult to maintain, guy is a genius and all his code is correct, clean and well made, but his thought patterns and how they end in the code are just too different, and all people that worked with him before also were geniuses and didn't care the code was "crazy".
Note: the "other geniuses" mentioned above, also quit when other companies made them great offer and the stingy employer refused them a raise too.