This doesn't stop when the abuse stops. Your brain still works that way. In time it can be rewired, but that is a very long process, with many years of misunderstanding and pain. These survivors of abuse don't mean to be weird or rude. Sometimes they have honestly never been taught any other way to survive. Survive, not live, survive. Some from birth, must fight every day to survive. These aren't adults with street smarts, or Bear Grills, with years of expert training. These are babies, toddlers, barely able to talk or walk and all they have ever known is abuse and how to survive.
It stays with you for your lifetime. You learn to only trust yourself. You are constantly vigilant. You learn the world is a hard and dangerous place. And you learn that even the nicest people can turn on you in an instant.
And when these times come, you can't go into your mind to find a safe place to hide, because in there is every person who abused you, every memory of the abuse, sitting, waiting, for you to see them again. There is no safe place in a mind built this way. Only the constant reminder that you have to fight to survive. Every day. And if you don't have the strength to fight today....... maybe you don't survive.