202109251019 Highly effective people are leaders
As a person grows in effectiveness, there comes a point where they can't scale beyond their individual time and effort. They necessarily have to start collaborating, delegating, and inspiring. To put this another way, there comes a point where they have to lead others in order to be more effective.
The absolute most effective people are excellent leaders.
I believe this correlation only goes one way though. It's certainly possible to be a great leader — depending on your definition of great here — without being highly effective. E.g. you can inspire people and coordinate their efforts on a path that's not effective or is counterproductive. If you take the actual outcomes into account though, maybe we'd say that this mis-leader is not, in fact, a great leader.