NCd for this, TMI! 
I'm 68 and have never masturbated. I've always had a low sex drive, and am fine with that. I was married, but my husband died a few years ago, and before that he was ill for ten years; and I have not had sex for 15 years... and am happy with that. I'll never remarry, never have sex again.
When I was a teenager, I didn't even know that women masturbated. Nobody ever mentioned it, though my girlfriends and I were all very open about what we were doing, how far we went, etc. I first had sex when I was 18, but only because everybody was teasing me for being a virgin! I could well have waited till I found "the one" and it would not have bothered me.
Some here are saying, use it or lose it, but so what if you lose it? If you don't miss sex, so what? Whatever sex drive I had, vanished after I had children -- I do believe I only had one because I really wanted to be a mother! Yes, I did like sex while I was active, but all drive left me after I had my kids.
If you don't want something, you don't miss not having it. I am very healthy, look ten years younger than my age, so I'm told, and have an interesting life which (before Covid) involved a lot of travel, and I'm very creative -- I believe creativity absorbed whatever nervous energy there might be! I also used to practice Hatha (physical) Yoga regularly, and still practice meditation, a practice which over time delivers a great deal of joy.
I'm glad the OP spoke up, and so many women have chimed in to say they are the same, and that it's OK. On the surface, it does feel as if every single person on earth is masturbating every night and can't live without it! Nice to hear that it's not that rare, not to feel any need.
There is the constant societal message that even as you age, you must be satisfying your sexual urge one way or the other, with a partner or without; and if you don't have one there's something wrong with you, and that as you age you become grumpy and frumpy without sex. We all know the cliche, "she's not getting any that's why she'd in a bad mood". That's just not true.
I wish there was more attention given to those of us who are perfectly happy without sex; that we were taken seriously; that it was recognised as a fine way to live and to age; that there is life after sex, and it can be very good.