Do you really think it is sad? That they have a hobby, or interest that they enjoy so much?
I don't. The elderly couple across the road from me love gardening and washing their car. Not my cup of tea, but they do it together, almost daily. I also know that they go to bridge together twice a week, and he boules, and she goes along.
I can't imagine they would want to contemplate the idea of not being able to do any of these things any more, and not sure why it would be sad that they enjoy it.
Some people enjoy a few drinks together, some enjoy chess, some enjoy eating takeaways, some enjoy potholing, some enjoy bungee jumping.. some things are dangerous/unhealthy, some are not.
Why do people judge so much what other people choose to do with their own lives? I honestly cannot understand it. What other people do really, really does not mean a thing to me. I hope they are enjoying themselves, and that is as far as my interest goes.
Until someone looks like they may need help, for god sake leave them alone! Live, and let live.