How safe it is to pin personal information to social media? At every registration they ask to attach your adress and phone number and I might believe that this information is vulnerable

I think that everything that's outside a bunker is not safe

If you're not an important person for the society (no matter good or bad) then you don't have what to be scared about. No one's gonna looking for you and no one's gonna need your information. But in general yeah, nothing is safe online. Continuing Nikra's thought: if you want to get something to safety - hide it behind walls or underground. For the online world, you might choose not to post your real information. Put a wrong location, sign up with a temporary phone number (for this are services like https://mobilesms.io).