Why not? Meeting new people can be enjoyable. There are a huge raft of social clubs out there for all sorts of things:- going out to vegetarian dinners, bushwalking clubs, orchid clubs, cycling groups. All these things can be done on one's own, it's just some people find them more pleasurable to participate in with like-minded people, and may not have any orchid-lovers, dog-lovers, vegetarians, whatever in their current social circle.
Personally I'm not big on social groups like this, I'm too grumpy, shy and misanthropic but if other people enjoy going to them more power to them.
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