Some people who are actually somewhat more on the introvert side but force themselves to socialize, think that it's in fact supposed to be a struggle, for everyone, and everyone who seems to enjoy it is to some degree pretending, and is more diligent in putting up with the discomfort, so it's a character quality trait how much you get your act together and endure socialization.
It's like hating blue cheese or certain vegetables or the taste of niche foods. But in fact some people do enjoy the food, and don't eat veggies because they must or have great discipline. In fact this is also true of exercise. It is something that people do enjoy, the pump, the endorphins etc. (Usually it does take getting to a baseline fitness level to make it enjoyable, so it's not a static personality trait.) Similarly with public speaking or working with people all day etc. Some people truly love it and look forward to it. It's not only that they are tough and endure the suffering better. They do like it.