Why do people go to nightclubs?
Some people go to drink. They like the feeling of getting drunk. Nightclubs should ensure that they don't go overboard with this.
It's an escape
Many people don't enjoy their job and nightclubs could be a way to escape and have fun for a few hours. It could be a good way to end a week.
Perhaps other aspects of their life are not ideal and they need some enjoyment.
The social aspect
Many people like to socialize. They might go out on a night on the town with their friends.
They may also enjoy partying with their best friend or significant other. I sometimes partied with a particular mate. When I had a partner I partied with although they didn't enjoy it as much as I did.
People may go regularly to a nightclub and become friends too. People may want to be around people with the same taste in music.
You might consider a quieter sound system in certain areas to allow for socializing.
Communities can form around a nightclub particularly if it caters to a specific type of person. An example could be a gay club.
People like to dance
Some people may just like dancing. Sure they can do it at home but it could be more fun with other people around.
People like dressing up
Some people like dressing up and looking good. going out gives them a reason to do this.
They go for the music/live entertainment
People may just like going out and listening to music. They could enjoy listening to DJs, MCs or live bands.
Music can be enjoyed in combination of things. A place to socialize and listen to music could be a good way to end a week as an example.
They may also appreciate the sound system.
They go to see if they can hookup
They might go to see if they can take someone home or stay at someone's place afterwards. I think that they should be cautious about doing this but it's also part of the nightlife culture. If everyone involved genuinely is into the activities there's nothing wrong with it.
I used to go in hopes I could hookup but I never did.
They go for eye candy
Some people just want to be around beautiful women and/or hot guys. Yes I am speaking from experience.
Men may like the women wearing makeup and in skimpy outfits. Some of the men go light on the clothes too.
Watching drunken people can be entertaining
Some people find humor in watching or dealing with drunken people. I do enjoy laughing at people occasionally.
My brother enjoyed checking around the streets to see if he could spot fights.
This is probably more applicable in LA but some people go out to spot celebrities. Some frequent specific nightclubs such Playhouse Hollywood, Nightingale Plaza, and Poppy LA.
Some people go to get VIP treatment such as bottle service. These types of people are typically wealthier and can afford the extra perks that a nightclub offers.
Enjoyment and happiness
Due to the reasons stated above some people just go to nightclubs because they enjoy the experience.
It is probably a combination of reasons
Most people probably go because of different reasons. I go to nightclubs because I like music, dancing, drinking and the eye candy.