A state's right to exist

What is a state's right to exist. Is it merely that it is a state and people have decided to live in it as citizens that it becomes a state? Or is it that the state exists and thus have a responsibility towards its citizen who relies on it for everything that happens in their daily lives. I believe that it is the later portion since a human being does not have choice where they are born, although they do have a choice to emigrate for economic, security or for any other individual reason but usually it is one of the two either economic or security reasons. Now nobody can question that why is a state existing since only the citizens have the right to decide but a state do have rights that make them justify their existence in the eyes of its citizens and the outside world. Although it has been written a thousand times before that what is a states right towards its citizens and outside world like secure them from internal and external threats, provide laws for them to work and prosper and facilitate their travel to the outside world. But to me the most important duty of the state and its right to exist is to provide security to its citizens. If there is no security for a citizen then what does the state's role in governing them. The state should then be dismantled and every citizen should fend for themselves.