I was a one of these “new hires” to a startup that was growing. It was chaotic because a lot of knowledge wasn’t transferred and we had to basically figure out a lot of the business logic because those original people were all gone.

I jumped ship after a few months and eventually the startup failed. I heard from former colleagues the main reason is those original people went to work for several big companies, who were all customers of this startup. They still held a grudge and persuaded those companies to stop working with them.