There is no doubt that the central cause of most altercations these days is due to alcohol consumption on a night out. This lowers their inhibitions and causes to act more emotionally. Some people are already emotional when sober, so they may lash out for small reasons when they drink. In addition, one of the main reasons of going out is to look for a mate, and this is a process that can get even regular mammals in the animal kingdom riled up.
Due to this, any places that stay open late during weekends or even Thursdays will see a disproportionate amount of trouble. This trouble occurs even among places where middle-upper class individuals are such as near colleges. This is all due to the alcohol culture that is legal.