Maybe my comment was too broad.
I only went to one - my 35th - none, and I mean not one of the most popular kids showed up. I asked others (some who were in the high school entourage of the popular kids) about the class presidents, the prom kings and queens, the top athletes, et al ... the answers were they disappeared no one knows where they are, they inexplicably stopped after the 10th reunion, they have health or other issues, and the old “Trust me, you don’t want to see them”.
I stopped going for a lot of reasons, but mostly because I had grown up and moved on. Life happens. FB came along and I was able to get back in touch with some. I don’t do FB anymore, but maintain a very limited presence there. That’s where I’ve seen the photos of the reunions. Very few aged well. Most were people who still lived within the state or a nearby one.