At Times It's Socially Practical To Know Things Other People Care About
This article won't be for everyone since it comes from a very pragmatic adaptation approach to the social world. Someone who's more into being true to themselves likely won't be into the ideas outlined below.
Some topics and activities appear pretty often in social situations. Sports, music, or TV shows come up in conversations a lot. When people go out to bars they often want to do things like dance or shoot pool. In my experience, it can be socially practical to know something about these kinds of areas yourself.
I'll clarify what I mean a bit more:
I don't mean totally overhauling your interests, more knowing a thing or two here and there
When I say it's socially practical to know certain things, I don't mean you have to learn as much about a subject as someone who is naturally drawn towards it, or truly like it yourself. More that even having a basic familiarity with a topic, or just being able to get by in an activity, can make a noticeable difference in how easy it is to hang out with people, versus knowing nothing about that area at all.
Knowing about areas other people care about helps your cause only in little boosts here and there
Just knowing about a topic other people are interested in won't make or break how well you do with them socially. I find it provides lots of small benefits though, which I'll cover farther down. Still, if you're not naturally compatible with someone, then just being able to hold a conversation with them about a certain hobby, or join in a certain activity, won't change that. And if your not knowing enough in a specific area means someone doesn't want to be around you, you probably weren't dying to be best friends with them anyway. On the other hand, if you already get along fairly with someone fairly well, and your lack of familiarity with a certain area causes a tiny bit of incompatibility, learning about it will make things better.
Obviously it's impossible for someone to keep up with everything
There are many skills and knowledge that could be socially practical to be familiar with, but no one person can realistically be expected to get up to speed on all of it. There's just too much to know. It takes time to pick up new skills, even just to learn the basics. Keeping on top of things like sports, TV shows, and the news can take a surprising amount of time. It's more a matter of, whatever you want to learn in your spare time, that's great, but don't put pressure on yourself to know everything.
If you honestly don't care about something, then you don't care
There are some areas that just hold very little appeal to us. Even if it would be practical to learn about them, we still can't be bothered, and we can live with the consequences. We accept we won't have the interests or knowledge to hit it off perfectly with every last type of person, or adapt to every situation we find ourselves in.
In a sense it would be great if we could make ourselves acquire new interests on command. I'm sure more than a couple have people have had the deflated thought of, "Everyone in my city is totally obsessed with football/basketball/hockey. My life would be so much simpler if I could just be into it too." It doesn't work that way though. If something really doesn't speak to us we may be able to learn to appreciate a tiny bit more, but we'll never dive into it as wholeheartedly as some people.
The benefits of learning this stuff
For the most part people are happiest by sticking to their natural and true interests, however adding the odd bit of practical knowledge can help your social life in the following ways:
You can hang out with people under a wider range of circumstances
When a lot of common activities that people enjoy don't interest you, you may find yourself turning down social opportunities because chances are good everyone will want to take part in something you're not that keen about. You may decide you're missing out on too many of those chances to spend time with people. Your natural interests may be obscure and esoteric enough that you can't easily form a decent social circle around only them. If you can learn to appreciate, if not love, certain activities you can take part in more outings.
For example, you may not live and breathe sports, but learn to at least be able to go watch a playoffs game at a pub with some guy friends. You may learn just enough about pool that when your mates want to play, you can join in, rather than sitting on the sidelines and being bored for an hour. Overall, you're hardly going to change to the point where you want to spend days around people who do nothing but talk about subjects you don't care about, but if those topics come up in passing you can manage.
You have more potential friends to choose from
If you're really disinterested in a certain hobby or topic you may filter out some potentially good friends, because they're into that pastime, and you want to avoid anything that has to do with it. If you learn at least a little about that area, you may still not love it, but at least be able to hang around an otherwise solid person who occasionally steers the conversation in a boring direction, or who sometimes wants to go to an event you wouldn't have chosen yourself.
It may help you access things that your natural niche doesn't provide
We all have a group we naturally fit into, and most of the time we're happy with it. Sometimes we occasionally want an experience our niche doesn't easily provide. Acquiring some more pragmatic knowledge and skills may help us access these things. For example, someone may be satisfied with their homebody, intellectual friends, but occasionally want to go party a bit. Learning about partying-related stuff may help them meet a second group of 'activity friends' who they can go to clubs with every now and again.
You don't feel as clueless and left out of things
Even though they may tell themselves otherwise, some people truly don't like the feeling of being the odd one out when everyone else is happily chatting away about baseball or whatever. It may irk them that they know nothing about these large topics that everyone else seems to care so much about. When you learn more about these areas you don't feel like you're on the outside looking in anymore. You don't have to be annoyed that these tedious, alien subjects keep cropping up when you're with people. You subjectively feel a little more at ease with yourself and comfortable in social situations. Not everyone may have this motivation - many people could care less if they're not knowledgeable about the latest TV show - but some might.
You can follow along with more conversations
We mostly hang around people who share our interests and outlook on life. Even then, we may still find ourselves in situations where everyone is talking about cars, sports, or a TV show. When you've learned the basics about a topic you can at least follow along with the discussion and not be totally bored as it all goes over your head.
You can contribute to more conversations
The more things you know about, the more chances you have to chip into a discussion with something relevant of your own to add. Even when you only know a handful of information about a topic, it'll often enough to make your mark on the discussion. Like three people at a party could be talking about a new band. You can jump in, say a thing or two about it, get a good response, and then sit back. You did okay in that small sub-section of the conversation. Better than nothing.
You'll be able to have conversations with people you'd otherwise have little to say to at that moment
Things like sports, movies, and TV shows are common-ground interests that you can talk to pretty much anyone about. Even if someone is totally different from you in terms of age, life situation, etc., you can always chat about a sport you both follow. It may not be the deepest conversation, but it's probably pleasant enough to discuss. Sometimes we find ourselves in situations where we have to talk to a person, and if we didn't have some standard topics to resort to, we'd have nothing to say to them at all. At a job someone may decide it's worthwhile to follow along with the shows their co-workers watch, just so they have something in which to relate to them.
You could pick up some fun new interests
Sometimes we'll start to learn about something for mainly pragmatic reasons and find we really enjoy it. Someone may never have been that drawn to music when they were younger, decide one day to see what all the fuss is about, and then discover all these amazing new bands and genres. They may learn they love going to concerts, and totally change the type of bars they frequent, based on the type of music they play. Or someone may start learning about sports for similar practical reasons. They may never become a diehard follower, but become a casual fan, enjoy watching the odd tournament, and decide to try a couple of new sports out in real life.