Maybe take a Master Gardener course. Over the years I've wanted to do that but my career, then small business and family obligations always got in the way. Finally a few years ago in a new place, at loose ends at age 60 I enrolled. It was pretty much all review by then but I was among "my people". There were mostly middle age and senior folk there (similar to myself, people who finally had the time/opportunity to do it) but about a quarter of the class were young people both male and female looking to start lives or careers with the knowledge gained and the certification of Master Gardener. There were all levels of knowledge and experience in that class from newbies with interest to very advanced gardeners. Even though I had already learned most of what was being taught it was well worth the money and time spent.
You describe yourself as I would have described myself in my mid/late 20s. Bored and disenchanted with rootless and often self destructive people, I was more nerdish and interested in establishing something solid and positive in my life. It took a while to connect with my husband (early 30s) who is also nerdy and into all things mechanical but I had already started my real life by then. I'd suggest that you've already established enough reasons to move on and start your life but fear and habit hold you in the rut.
If you can't take a class, maybe there are local meet-ups or gardening groups, also maybe work a season or intern on a local organic farm or orchard. Habitat for Humanity is always looking for help building their donation homes. There are tons of local opportunities here in my area such as groups removing invasive plants, cleaning streams, tree planting, non-profit historical farms or gardens looking for help. As we've rebuilt our lives in a new place I'm too busy to take advantage of most of them now but they are there. Like a concert they are often advertised briefly in local papers and all it takes is going and participating. I think you'll find this crowd more to your taste as most of these folks tend to be self directed, health conscious, non-smokers (or at the very least polite about it) and are not aimless partiers.
Good luck to you.