Rather, you should strive to be fair and create an enjoyable experience. If your goal is to destroy the player characters any chance you get, then you are doing it wrong. Your responses to the players, the situations you present, the challenges you create, the stories you build together, all of it should be balanced so as to provide an enjoyable experience for you and your players.
However, the goal of any RPG should be a fun time for ‘’’everyone’’’ involved. That means everyone or anything the players may come across or interact with is controlled by you. As a DM, you control everything and everyone that is not a Player Character (PC for short).Those descriptions are usually exaggerations from people who are either ignorant of what a DM really is or the extreme interpretation of a half-truth. The descriptions you may have heard of a Dungeon Master probably range from 'the one who does all the work' to 'You are god here'.