Rebellion is as normal for teenagers as acne and hormonal rage, and teens can be total terrors while they're in the midst of their "broody" phase.
They naturally don't see it as a phase, but their parents know it usually is and hope the phase will end sooner rather than later.
But by the time they're in their 20s most people have outgrown that Emo, Punk, Raver, Metalhead or whatever phase they swore was their true face coming to light in their teenage years.
Which is why it's absolutely delightful to see how these teen rebels look when they're all grown up, and for most of these "pioneers of subculture" the difference is like night and day.