I don't post under a real name for safety reasons.
Using sites like anywho.com, etc. people can find out your phone number and address.
One example I can think of is:
You post a picture of your firearm collection; say an extensive one, worth at least $5000 +. Someone notices that you live in Anytown, USA; which happens to be near where they are. They now look up your name, get an address (won't work everytime, but why take a chance?) and start planning how they will break in and steal your firearms.
I understand that is far-fetched, but there are a lot of parents who are missing children because of the internet. If in today's modern world everyone is on the internet, that means there are a lot of bad people too!
John Lane, I found a list of 5 persons with your name in that area. It would be easy to narrow it down using the phone number and addresses also provided. I obviously won't go any further for your safety. God knows who could end up reading this.
Insert witty, comical, and/or significant quote here.