Social isolation is a huge problem. There's stigma around declaring it. I'm doing my part to address this problem right now: Any HN'ers in downtown Vancouver reading this post, let's grab coffee near Robson Square. My email is in my profile and synced to my phone so I will reply promptly. I've been just reading principles.com (from the other HN thread) and inspired to take action.
To some extent, Meetups help. It's not just an opportunity to hear about the latest in a filed that you have an interest in, but also an avenue to meet-and-greet.
Btw, nobody showed up yesterday but I haven't given up. I'm here from 9am ~ 5pm near Robson Square. Coffee (or tea) is on me.
If you are not in Vancouver then shoot me an email, you can talk about anything.