Look at it this way: the family has no where to turn with young Somchai doing his thing with all the peer pressure around him. No guiding adult in his life (they're all busy working or on drugs themselves). The nuclear family is disappearing in thai society. He turns to his buddies for relationships and a common theme amongst them is: feel good... any way to achieve that be it alcohol, sex, or drugs. You can say that about many drug conflicted countries.