It's the dice man, it's the dice. I love rollin' 'dem bones.
Not really. RPGs for me have always been about friendship. My friends and family are, were, and always have been geeks. I remember that, when I was a little kid, my extended family would start rolling up characters for a campaign they ran during Thanksgiving dinner occasionally. When I got older, my friends played various PnPRPGs, but mostly D&D. When I got to college, my friends played RPGs, so I finally got around to trying what I'd already wanted to try.
So it brings back memories of lost times, lost people, lost stories, and lost innocence... a lot of that which is lost for me comes back, even if only for a time. It's a comforting feeling.
Even the entire edition wars here have that tinge of familial security. One of the longer debates in recent memory involves D&D editions, but it's always a sort of recognition that we both play, but in different ways. In my family, we've got new guard, old guard, and at least one grognard, so there are always some minor arguments, but they're usually ones that manage to keep the line of civility, though there have been times people stopped speaking to one another after an edition argument.