I see people asking about friendships on here (and elsewhere) all the time and I commiserate. But over the last few years I have been greatly expanding my friend circle very naturally. And for baseline, I'm 39, married, no kids (yet), and a full time SRE.

For me its been all about hobbies.

A few years ago i started asking myself "What would young Colin want?"
IE, what was I interested in as a child, that as an adult I could learn from.

I realized there were big aspects of who I was, or how I grew up which were simply missing from my current life. So I started to add them back in in the simplest ways I knew how.

For me that meant that over the past 5 years I've added, short backpacking and canoe trips (rental canoes), learning to snowboard, playing golf, Ice Climbing, Photography, going deeper on my electronic music production.

The biggest wins have been snowboarding, camping, and by far golf.

With snowboarding, I was able to get some existing friends and then coworkers to start going on quick 3 hour drive day trips. A few existing friend got back into the sport, a coworker started and bought gear, I met 3 more coworkers outside of my team by organizing work trips. I just went with two guys this weekend who were old workers from a few years ago, its our 4th season doing these trips and Ive probabbly expanded my circle from 1 friend to about 10 who have participated.

With camping, it was similar. I had one friend who started with me, then he invited some of his friends and they invited theirs. The group keeps finding more people and coming up with new ideas. Weve probably got a circle of 8 people who have gone and weve done about 3 years or regular trips. there are more people who WANT to go though, its just a matter of time.

BUT GOLF IS THE REAL WINNER.
Everyone seems to know these days of the "third place" problem, or the "Bowling alone" problem. Golf really has avoided these issues and really after 2020 lockdown expanded a ton. With golf, first of all... you can go alone, and you will meet usually 3 strangers every time. And in the last 3 years of doing that, I have met amazing people 99% of the time. really it would be very difficult for me to name a time i met someone i didnt like on some level... and some of the people ive met have been amazing. BUT, the old adage that "business happens on the golf course" is still true today, even in tech. We have a golf chat at work, and I regularly play with our CTO and other bigwigs at the company that I would never have met otherwise. In fact the very first person I met at the company (its a remote job) was the CTO... because we just both wanted to play golf. I am personally NOT a networking guy, when i play golf.. i dont talk about work. some do and that fine, but I let others decide. Besides work, I have about 10 people that I have kinda integrated into little outings. some are just terrible golfers and we go to terrible cheap courses and enjoy the sunshine, losing balls and then finding them in the woods. I have a best friend at work because of golf, and my work connections spread far over the company into areas i absolutely would never have ventured otherwise. Ive played with people from finance, law, tech, commercial real estate, medicine, advertising, film production, people from other parts of the world... so many that I have played with over the last few yearsthat it is simply uhh, mind boggling. I could go on and on about golf, but im gonna shut up about it.

Start doing things you love, pursue things you think are out of reach, bring a couple people you might know along, ask them to bring their friends, ask to play again when you meet someone cool. Its often awkward!!! and often fails... but you have the ability to open up your own world, and the world of those near to you.