I built my first computer when I was 11, but it didn’t age that well. When I was 15 I spent most of my evenings playing World of Warcraft, but my scrappy computer couldn’t keep up. Because of that I decided to learn how to create my own “addons” with a huge focus on increased performance (addons modify or replace aspects of the user interface).
I was able to create addons at a fraction of the size and at much higher efficiency than what was available at the time, and over time my addons have become extremely popular.
I don’t play World of Warcraft anymore, but I still do update and develop new addons in my spare time.