Why does it seem like most people don’t want to expand their social circle or meet new people after age 25?

[SaraSmithishere]

I have noticed that my coworkers have never gotten together after work, and people don’t seem to want to introduce themselves to others

[coldmarch]

What you observe is probably true, and I think this is because of multiple reasons: at 25-30 you can say a person's personal path (or the most important part of it) is finished, they know what and who they are, they explored alternatives, they took decisions, and became a quite permanent version of themselves. That makes them way less interested in new social relations than before, as, often, social relations are just a mirror of yourself to do experiences and grow until you settle. And the activities you'd be driven to do are also reduced. Plus, at that point of the life you've seen a lot of bad traits of people you can now recognize from early hints, and have been disappointed a lot, so you're often demotivated to get too close to someone and afterall you don't need it so much, as you can self-support yourself for most of the small issues, or through a longer lasting partner than the ones you had at 20. All this, not considering the amount of time removed by: job, marriage, house, kids.
These things make people close in their own circle of comfort zone made by a small amount of safe contacts, hardly changing during the time. This causes people who didn't take these steps "on time" to feel much more lonely and excluded than they were in their early 20s, often bumping into weirdos who are not settled "because reasons" (I am one of those by the way).
So, some solutions could be: meet younger people, in real life or in online communities through a shared interest; don't get too demotivated, because not everyone is settled and not every "non-settled weirdo" is necessarily a weirdo; find a partner who has already a good circle of friends to merge with.
Regarding job: colleagues are not meant to socialize, this is normal (and in my opinion better). Social issues can create sides between colleagues and other issues that would end up obstacling the job tasks themselves. It's not a "rule" but I think it's perceived by enough of your coworkers.

[exitseven]

People get married and have kids and that takes up all their time. I am in my 50s and all of a sudden I realize that if I got hockey tickets I would have a hard time finding somebody to go to the game with me.

[exitseven]

Thanks for the MHO😎

[Adam1978]

Moderation, you don't want to be around the same people all the time, so you want friends from other circles in life. So you don't end up talking work on your free time.

[007kingifrit]

think of how you met friends when you were young. it just happened. now it doesn't just happen. you need to do it artificially not just meet whoever sits next to you in school. it's sad but modern life isn't built to have community

[spartan55]

That has everything to do with who they are, not how old they are.

[SignedAutographs]

Because I'd say on the most part that most people, are introverted

[IsoUser]

Why wouldn't any guy be willing to meet a girl over 25?

[Pyrofox]

Its the quarter life panic attack that happens.

[UniquelyBasic]

Why mess with something thats not broken?

[EaterPeter]

Coz it's a costly hobby

[eagle1951]

I like meeting new and interesting people