It was a dark and stormy night...
At work I was given the task to improve a template which required iterative calculations, and so my thought was to use VBA macros. Talking with a friend about the problems I was having with writing what I wanted, they suggested me to check on Stack Overflow. When I needed to ask questions which were not already answered, I created an account there.
In parallel with this, I used to spend some time on a blog of F1 aficionados, who filled the idle time between a race and the other talking about various topics, ranging from physics and thermodynamics to the feasibility of F1 racing on the Moon.
It didn't take long for my eyes to notice, in the HNQ section, the intriguing titles of some questions posted on Worldbuilding, which somehow resonated with the idle discussions I participated in that blog.
From there to creating an account also here, the step was short. And while my activity on that blog dwindled, it was compensated by an increase in activity here.
Then when I posted this answer and received so many good reactions, that's the moment I got hooked to Worldbuilding.
Honorable mention to this other answer which started the usage of the word potatoid.