In the "wins the lottery" and "left for a new job" cases there is at least the possibility of knowledge transfer. I was brought in on a situation where the prim

In the "wins the lottery" and "left for a new job" cases there is at least the possibility of knowledge transfer. I was brought in on a situation where the primary IT lead suffered a stroke, rendering him unable to communicate for weeks. We had to reverse engineer everything, crack passwords, rebuild servers, etc. This is, unfortunately, my go to example of the need to mitigate risk of a central point of failure.