The other piece to that is in most cases these events are the only time some groups of friends or strong acquaintances have the opportunity to hang out and bond face to face. confer. I would argue that is human nature to want to celebrate with friends who you only see on rare occasion and drinking tends to be the most easily and socially acceptable way of doing so. In many cases it is at these events that many times acquaintances become stronger relationships through just hanging out as people post conference.