I started riding bikes about 11 years ago and volunteering about 10. I've met a LOT of people, made some good friends, and after accomplishing some goals felt a nice sense of achievement that work stuff just doesn't quite get me. Pretty sure I'm a better person than I was 10 years ago, and the social and community aspects of volunteering stuff are almost guaranteed to be a big part of that.
(Note: Long-time lead-type IT person here who volunteers as a board member, trail builder, and map maker for a local mountain biking group. What I do at work is helpful for the volunteer stuff, but as it's not related it's something neat that I look forward to; not just more work.)
I'm not saying there are not busy people who volunteer or go to church, but I think there's a "have time and patience" factor associated with it.
The average Churchgoer works full time and has a family. They don't have time for Church, they make time for it. It's all about priorities.