I didn't mean sports clubs. I don't like sports much either other than the gym, where I go alone.

But in my city Meetup.com has a huge amount of clubs and groups for basically anything, and I'm in Barcelona so the city isn't even that big and it's not all English-speaking (which I guess may be more likely to use Meetup).

There are sometimes local Facebook groups for stuff as well, I went on day-trips to various places like that.

I know my colleagues who are into tabletop games and D&D go to those groups, I personally just went to language exchanges and hiking/tourism groups. There are even groups for local video gamers etc. as I guess it's nice being able to meet in person too.

There are a plethora of groups for adults. There are groups for tabletop/board games, music, movies, sports, hiking, etc. There's likely groups near you on meetup.com or facebook groups.

For music specifically there are local scenes. If you go to local places consistently, you'll see some of the same faces. Etc.

I like programming, but I would find it very boring to only be friends with people in the same industry as me.

Meetups or facebook groups select people who are into meetups.

For meetup.com specifically, maybe, but there are plenty of facebook groups around hobbies that aren't specifically "meetup" oriented. You could look for organizations specifically in your area, and chances are they'll have a facebook group, facebook page for events, or a meetup account.

I also don't see this as an issue. If you want to meet people, that's a great way to do so. I've done it across America and in Korea, and I have made many friends from it.