I got into collecting baseball cards in the early 90s because that was the thing for a grade-school buy to do, but that lost appeal for me over time. Now my cardboard addiction of choice is Magic: The Gathering, and playing games with other people is a big part of its enduring appeal for me. Hobbies aren't just a solo activity, and whether clubs or games, it can provide a low-key social outlet for us introverts, too.