Where are the core contributors?

We as developers use WordPress on a day to day basis – implementing client projects, writing plugins, launching services. And yet, the number of us who spend time participating in Core development directly is significantly low.
Why is that? Is it only a lack of time or are there other more sensible reasons that keep developers from helping out? My session will deal with the hurdles to overcome, philosophies, code quality and how you can benefit from contributing – an investigative experience report from a young Core contributor.