The fact that on Saturday night while people are out in the town I just want to get home to my computer and check geekhack....
This could also just be a symptom of getting old. I have no desire to go out on Fridays and Saturdays anymore, whereas in my 20s I had FOMO.
Then you see 50 year olds out when you do actually go and realize you'll get FOMO again at some point in your life.
Other than material goods I've never really had the FOMO, in my teens I was busy gaming although I guess it would have been the FOMO on double exp and such lol
I've never actually had a desire to go out to social areas like bars and such since I just always found it less fun than everyone said it'd be and it just seems like a lot of work and a waste of money.