I think I saw this quote somewhere else on HN about a post lamenting how difficult it can be to make new friends after age 30 or so:

Finding new friends as an adult can be exceedingly difficult, but becoming a friend to someone is surprisingly easy.

Lots of people (and if I'm being honest I'm one of them, so no judgement) just sort of expect friendships to come to them. But if you actually do the hard (and somewhat socially risky) work of inviting people to do things, offering to help unsolicited, organizing gatherings, etc. new friendships are much easier to come by.