I'll break it down for you,
, :
~simple logic part~
People need money to make movies. People earn money by investing money in movies, and selling them. If you download movies instead of buying/renting them, they do not earn money. If they do not earn money, they cannot make more movies: making movies cost money. Result: no more movies.
~difficult logic part~
(carefull if you had trouble with the previous part, best skip this part and go directly to whatever you were doing)
Now you want to watch movies, and you dont pay for them. That means that you watch movies, made from money paid by people who DID buy the movie, giving the director and actors their money, so they can make another movie.
~Very difficult part ~
(carefull, metaphors used here!!)
Now, lets say, you buy a cookie. And some stranger starts eating from your cookie, you are not happy. It cost you money. The stranger had no right to eat from your cookie!
Now I will project this metaphor, on the aforementioned situation:
As downloader, you are "eating" the "cookie" of the people who pay for movies.
(All this should be read with a wink ofc, but that's the general idea anyway)