I had two motivations. One was to teach myself a language other than Fortran, and the other was to make a forum that was designed around thoughtful content and discussion. The first posters where friends that I talked into joining.
I've been online since BBSes, and was a very early Redditor. Making a site that is fertile ground for quality interaction presents a lot of difficult and compelling problems. We are still working on it.
thenewgreen joined a few months after I started, and understood the goals completely. He also had the idea to incorporate the logo into the site's mechanics. (I first created the logo when spray painting it onto a t-shirt when I was 14). His passion has not flagged a bit.
insomniasexx crashed a Google hangout meeting we were all having, and after a short while, we had to make her part of the team.
akkartik was the first coder besides myself. He knows Arc better than most anyone, which was a godsend. He still has commit access, last I checked. :)
forwardslash joined shortly after akkartik left, and like everyone on the team, he was an active user beforehand. He now carries the bulk of our coding expertise.
All of the current team members have day jobs/classes, and all the retired team members remain good friends.
We are likely to be announcing a new member to the team soon. :)
But that's only part of the story. There are numerous people on this site that have had just as much influence on its evolution. I am going to regret names that I leave out, but other early users that have influenced the site include: alpha0 theadvancedapes cgod NotPhil caio lil mike ecib steve minimum_wage kleinbl00 thundara lessismore JakobVirgil bfv Mindwolf zebra2 ooli and StJohn. Those are some of the earliest, I think all members for more than 1000 days now.