WIY:
Two points:
1) It is quite possible that you know someone who went off the derech because of rap music. However, anecdotal evidence does not translate to “every.”
2) It sounds like your experience was really painful, and I have no idea how close you were to this person, but you have NO WAY of knowing what caused his pain. ANYTHING could have been happening in the background. I have friends who listen to rap who are NOT like how you describe- the sight of a million white sheep doesn’t prove that sheep are only white, but the sight of one black sheep will immediately disprove the hypothesis. You could easily be right, that rap music brought him down, but a) it may not be so simple, and b) that doesn’t mean that rap brings EVERYONE down or that everyone who goes down did so because he/she listened to rap.
In fact, I’ve known of people who were driven down by an external factor and began to listen to rap music (which I hate, BTW, and which I think is quite poisonous) or other “rebellious” music if only because it was rebellious, as a manifestation of rebellion.
Actually, a third point:
3) I wasn’t trying to insult you above. Look at what I said and you’ll figure out why I said it. (You may have already, but I just wanted to make it clear that I’m NOT trying to be cruel in any way, just trying to make a point.)