1. As Pbroy said: When you are poor and therefore pirating is the only way to enjoy stuff on your relatively expensive console/PC.
2. When you've already bought the game/movie.
3. When the game/movie are really old and/or only small amounts were sold.
4. When your paying over $20 more than people in the U.S.A.
B.T.W: I pirate games and movies and I have none of these problems except for a little bit of 1 and 4.