Recently @vambenepe tweeted

An excellent developer who doesn’t think like a PM is like a tennis player with awesome shots but who doesn’t aim.

This tweet reminded me of another excellent analogy that I’d heard many years ago:

Developers are like cars. They have an engine that determines how hard they can work; a gas tank that determines how long they can work; and a compass that determines which direction they head in.

In other words, it doesn’t matter how clever you are and how hard you work. If you are not creating something of value to your customer then you are wasting your time.