There are roughly 70 code contributors to the logstash project as of today. Many more exist as helpful folks on IRC and the mailling list. Others post awesome bug reports and feature requests. The community is simply awesome.
I've been working on logstash for about 2 years. All as a hobby - all part-time. About 70% of the current content (commits, 'git blame' lines, etc) are by me.
Unfortunately, I've never used logstash in production. (Embarrassing, I know!)
I'm embarrassed to answer user questions like "How do I optimize elasticsearch's storage?" with "Sorry, I've never used elasticsearch outside of my laptop."