The manager who becomes tyrannical in pursuit of power is a tale as old as the workplace. Some people just can't adjust to having any kind of responsibility for other people, and it is those who have to work under them who usually have to suffer the consequences. A boss is somebody who can dictate whether a job is pretty good or a living nightmare, and the bad ones are likely to cause more than a few resignations.
When you are an employee who works under a terrible supervisor, the most aggravating thing is that it often feels like there is not much to be done in the situation. Even if you complain to upper management or HR, they are not necessarily going to be on your side. On the other hand, dealing with the issue yourself could put your job on the line. Even if it is a role you want to leave, it is better to do it on your own terms. The result of this dilemma is that most employees simply grin and bear their manager's unacceptable behavior. However, others find a way to let their opinion be known.