3. Hackers Ruining The Game
The most frustrating part of any online game is those who have the upper hand by making their character have an unfair advantage on other players by hacking the game. Hackers have been known to make their characters able to see/walk through walls, be invincible and even aim automatically. It has to be said that the game developers are often on top of these problems and create updates to patch vulnerabilities in the system, locking the hackers out.