Imagine your goal is to climb the highest mountain. The problem is you are in a foreign land with no map. You might decide to follow what engineers would call a greedy algorithm: at every step you simply take the one that increases your elevation the most. You will likely find that you are soon standing at the top of a hill. As you survey your progress you are almost certain to see much higher peaks in the distance but you can’t leave your hill without going downhill. You have arrived at a local optima.
I see this happen all the time to people in their careers. They work hard and get to a point where it isn’t obvious that there is anything else they can do to grow their impact where they are. At the same time, they can’t change jobs without reducing their level of impact, at least for a while. They end up stuck on that hilltop for fear of going into the valley.
We can not expect monotonic growth in our career. We can not expect our managers to move the earth around us to keep us challenged. If we aren’t willing to take risk then we are relying entirely on having picked the right hill to begin with. That is a tall order given that we pick our starting position when we have the least information about the landscape. In my experience people caught in the impact trap eventually become unhappy and quit. They randomly restart somewhere else rather than pursue the higher mountains they can see in the distance.