Honestly i think this is because they are easily accessible, many people do it and look at how strict regulations have gotten, you cannot hit a kid anymore neither can a teacher which results in these teens taking drugs as they are no longer afraid of authority, they are not scared of their parents anymore or teachers. Many states are starting to legalize it which seems OK to them and plus technology which turned these teens into depressed clusterfucks who cut themselves and do drugs because of bullying.