Being so focused on leading and implementing a Maximum Effort software development project that I failed to notice a couple of employees fatally undermining my position until it was too late; I was purged immediately after delivering version 1.0.
This triggered a disability that I later learned I was genetically disposed towards (and that eventually totally disabled me) and fairly quickly killed the project and soon enough the company.
Some people are "in it for themselves" but don't have the wit to realize it's not a zero sum game and that some people are indispensable in a small startup (in my case, I was the architect and the only person who had what it took to make one critical part of the system work (with only two other programmers I hadn't had a chance to teach that yet (raw C Windows GUIs interfacing to 3rd party libraries and our server, there was a lot of unrelated raw learning required there))).
This triggered a disability that I later learned I was genetically disposed towards (and that eventually totally disabled me) and fairly quickly killed the project and soon enough the company.
Some people are "in it for themselves" but don't have the wit to realize it's not a zero sum game and that some people are indispensable in a small startup (in my case, I was the architect and the only person who had what it took to make one critical part of the system work (with only two other programmers I hadn't had a chance to teach that yet (raw C Windows GUIs interfacing to 3rd party libraries and our server, there was a lot of unrelated raw learning required there))).