I'm only 54 - and on most of my group rides that's about average. Quite a few of my friends are 60+. These are not 'old man' rides, but just the local open groups. Occasionally there's a junior from a development team or something, but not that many.
I like riding with others - competition brings out the best in me & there is also safety in numbers. However, lately I've found that I prefer to be either on the front or rear of a ride, seldom in the middle. Too much squirrely stuff goes on, even with experienced riders. My Sunday ride is the best - just a small group of friends that I've known for years and really trust.
I do find myself solo a lot, too. But that's not always by choice (!)