Why did hobbes argue that citizens should form a social contract with their government?

According to Thomas Hobbes Social Contract Theory, "Morality is the set of rules governing behaviour, that rational people would accept, on the condition that others accept them as well.'' He argues that those who live under a government are parties to a social contract where each and every person agrees to follow the laws of the state on the condition that everyone else does the same.  He argued that this way, we all become relatively safe from each other and so we all benefit from one another from the social goods that will result.
Thomas Hobbes theory further says  "the state exists to enforce the rules for social living, while morality consists in the whole set of rules that facilitate social living, therefore, the need for government to enforce basic rules of social living while morality encompasses rules important for social living but are outside the scope of the government i,e, do not abuse people or no reason.