Because Vegamovies is not a charity. They have server costs. If they aren't charging you money, they are charging your compute power . A more insidious payload is the Infostealer. You click the "Download" button (which is actually an ad disguised as a button). You download a file named movie_1080p.exe . When you run it, nothing appears to happen. The movie doesn't play.
Don't download the file. Close the tab. Rent the movie. Sleep better at night. what if...%3F vegamovies
The internet has taught us to believe that "free" is the default state of media. But it never is. Either you pay with money (streaming services), you pay with attention (ads), or you pay with security (piracy). Because Vegamovies is not a charity