A poison pill is something that contaminates an entire batch. It doesn’t need to be large or obvious. In fact, the most dangerous ones rarely are. A tiny impurity, introduced early and left unchecked, can cause immense damage, especially from the inside.

Lately I’ve been interviewing companies to purchase, reflecting on my time at Amazon, and thinking about what it actually takes to start and run a company. Maybe it’s apophenia, seeing patterns where none exist, but once you notice certain types of people, it’s hard to watch the damage they cause.

Teams are surprisingly resilient to poison pills. I know our engineering team certainly was. We had one person who couldn’t write a line of code without a bug to save their life. Not a problem, every change required a two-person review, so they couldn’t do any harm. They weren’t pulling their weight, but they also weren’t actively harming the system. As a lead, these cases are easy to identify, isolate, and either coach or route around.

Middle management is where things get dangerous. There’s no real check or balance. What are you going to do, tell your director peer they’re being stupid or block their initiative? Escalate sideways? Good luck. I know most of you have seen this dynamic play out, whether firsthand or through the slow-motion collapse of a project that “made sense at the time.”

Upper management is almost a moot point. Once you’re an executive, you have real ownership either financial or reputational, or both. If you’re a poison pill at that level, you’re poisoning your own well. Ironically, one of the companies I looked at acquiring has exactly this problem. I have to weigh, even without that person is the well already too poisoned to recover?

If someone in an executive or even founder role can actively harm a company and still be in charge of a relatively successful company… why exactly can’t I start one, or at least run one?