Well they seek the effect of course What's the effect of alcohol? The more you take, the less lucid you become, that's what you get People who get shit faced are looking for just that. Now maybe they're too lucid/realist for their own sake, so they compensate like that, by distancing themselves/escape from a shitty reality through loss of lucidity. Or maybe they aren't objective, and tend to see their reality in a way that is darker than it actually is, it doesn't really matter, they still need to drink for the exact same reason in the end Now you also have people killing themselves with drugs, slowly, it's a way to get attention, to scream for help somehow There is no single easy answer. That being said, drugs are an escape plan essentially