That largely depends on the style of music.
Go to a modern prog show and the entire crowd is still just there to watch and absorb the performance.
Go to an alluvial show or similar band and everyone's there to let out pint up aggression and constant sensory overloaded energy in a semi-healthy way that doesn't damage your social life the next day

these shows aren't as violent as they look either. When someone gets knocked down, multiple people pick them back up, if someone is being overly physically aggressive or dominating it gets handled immediately and that person is usually removed from the venue. You sign a social contract by entering one of these shows, and you are always held accountable for your actions. Usually a couple dudes twice your size covered in tattoos and piercings with big ass beards will pull you aside and quietly tell you to calm the fuck down or get the fuck out.