I saw such kind of situation not too long ago. A superstar developer who co-founded the company over 10 years ago, busy in the most challenging area of the code.

A couple of years ago, the company was bought by a large international holding, the management changed.

The guy with his team just rewrote the core of the business engine, which took like one year of work (really big project). Management decides that he and his team are too important (and paid) and re-engineer the process to diversify and reduce risks and interconnections.

He was appointed as a coach in a new team of juniors (cheap outstaff) to transfer knowledge. Of course, it turned out that they were not able to handle this level of complexity - I'm not surprised, it was a really complex subsystem and really cheap outstaff - and they started to complain.

He lasted a couple of months and was fired the single day after he approached one of those developers to at least read a school book before making statements he couldn't even figure out. Yes, it was kind of rude, but from my point of view, he had a point, and was very patient.

I know for a fact that some manager got his bonus for getting rid of a toxic developer. However, development was halted and reversed, and several senior developers left the company out of frustration. Who did win?