And most people that drink every weekend don't "need" to do that either... It's about making the most of the situation. If you're going to a bar or a sporting event and you KNOW that being drunk will make the night more interesting, then it makes sense to drink.
Say you have a favorite burger and it tastes really awesome with cheese. Sure you could make it without cheese and it would still taste great, but why not just add the cheese and make it the best burger ever?
I don't really believe in doing any drug to make a boring situation more interesting, but if I'm going to do something that I know is going to be awesome, I'm going to try to make it as awesome as possible. That said, there are very few situations where being sober ISN'T the most fun for me... But I'm not going to judge others for doing what makes them happy.
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http://soundcloud.com/thundersheep/lunatic-asylum
http://soundcloud.com/thundersheep/summer-rain