People get more conservative as they age. Ten years is a long time; if the same people on the same forum stay for that long there is bound to be a shift in politics. People I know on the "right" have become much more centrist, and people I know on the far, far left have started to moderate themselves and move toward the, I guess "not no wingnuttery-left" is the way you would call it. Not exactly a move to the right but more of a move to "I have all this life experience now and can see other people's opinions in a non insulting manner." I'd be a lot more interested in seeing if there has a been a significant "staying around" of the old farts with 8-10 year old accounts on reddit. I bailed, deleted all my comments, killed my shitposting account and know of at least a good dozen other people I met when I started doing science outreach that don't bother with Reddit or deleted their accounts.