Many game developers say that modding it's great way to check if game development for you or not and I agree with them. Not everyone can try to become full-time developer for many reasons, but almost anyone can make some item for game they like, write story or make map.

I spend some time on modding in long time ago and now spending my free time on open source engine for game I play since 1999. Reason I doing that is to make it feature-complete so I can eventually implement my own additions to game mechanics and see how they going to work.

Also I always wish to work in game development, but life don't always work as we want to. I'd helped to test and support other commercial game as volunteer and now my own attempt to check how it's looks like to make games.

I feel like other people have similar motivation.