Why are some people so private?

[no]

I don't understand why other people must post EVERY BLOODY DETAIL ABOUT THEIR LIFE on social media.

No, no one cares what your 11:00 am snack looks like!
No, no one wants your phone to update your location every 20 minutes!
No, no one cares that you went to Taco Bell again!

She doesn't feel it's anyone elses business what she does when the front door closes and I agree with her... I'll post a photo of something I cooked if it is something I'm proud of having made and when my cat fell off the railing and hurt his foot, I posted about it to get help... But by and large, other than to REALLY VENT, I don't post much private stuff because i don't think anyone cares and I don't think anyone should know...