Answer: Because they are afraid of being killed.
Explanation:
In Act 2, Scene III, of "The Tragedy of Macbeth" by William Shakespeare, Malcolm and Donalbain feel they need to leave Scotland because they are afraid that the man who killed their father might attempt to kill them. Malcolm and Donalbain are King Duncan´s sons. Malcolm is the heir to the throne of Scotland. King Duncan has been murdered. Malcolm and Donalbain think that it is not safe to remain in Scotland because they can be murdered by the same man who killed their father.
