The hormones changing during the period from 14-18 is a big
onset causing them to feel rejected or not misunderstood.
These teenagers will take opinions from their peers who are no
different from them and commit more mistakes. As a result of stress
from work, problems and mistakes, they believe everyone is against
them.
They are the most sensitive at this age, easily manipulated by
older peers for benefits and they felt wanted. They wanted others
to understand and these older peers lead them into the wrong
steps.
Thus, 'rebellion' against all forms of rules seemed to them the
most appropriate way of life. The cool thing, the in thing. They
listened to their 'cool' pals who lead a bad lifestyle and indulge
in sinful lifestyle like doping, smoking, fighting, stealing, sex
and abuse of vulgarities. They will then wreck their life when
these 'cool' pals backstab them, their lovers desert them and
indulge more in sin.
Thus, they lost control and felt unwanted, thinking there was no
way back and dying is the only way out.
Anyway, for more information... pick up a book on growth.