I was able to reconnect with some old friends. And because of facebook some that were barely acquaintances are now some of my closest friends.
Your age has little to do with it- I’m turning 49. My mother and her friends are in their 70s, not at all techie and all on Facebook. You don’t have to align your life around it - I certainly don’t. But I have a lot of friends and family who don’t live close by , and who I want to keep in touch with. Before Facebook, it was mostly Christmas cards, weddings and funerals. There was the occasional phone call, but certainly not even one to each person per year. Now, if all my friends and family lived close by, and I saw them frequently, Facebook would not be so useful to me.
You can set the privacy settings so that only friends see your posts,photos and list of friends. You can put people in groups such as “acquaintances” or “close friends” which will determine which of their posts you will see and you can restrict your posts to one of those groups . You can set it up so that only “friends of friends” can send you friend requests. My daughter has her profile set up so that non-friends can’t even find it. It doesn’t necessarily take much maintenance- you can choose a default setting and stick with it , or you can choose a default option and still use individual settings that are more or less restrictive for individual posts.