It's actually not about preferences. Introversion means that social situations exhaust you mentally and extroversion means that a lack of social situations exhausts you mentally.
I'm introverted and even though I don't hang out with large groups of people much anymore, when I used to skateboard which involved hanging around with 10+ people for 6-8 hours every weekend day, I'd be so mentally drained that I'd have to spend the whole Sunday just being alone recovering.
I've always had a lot of friends so I discovered really early just how introverted I am.