Do they believe they are making some individualistic ideological, cultural or fashion statement? Or are they simply fulfilling a need to belong to some peer group and want to go with the flow?
Do you believe that individualism lies in what you wear and what you listen to? How about your mind?
And why spending money on alternative clothing is more 'naive' than spending money on brand mainstream clothes (which are even more expensive)?
Really, that's ridiculous. These are not the subcultures who make up an ideology to clothes - usually these are people who share some sense of aesthetics, so they like similar kind of clothing. And the non-subculture people desperately try to find some ideology in it, which isn' there. Why do so many people assume that the ones who dress differently do it in order to say some statement or prove something? Is it really so hard to understand that people wear alternative fashion BECAUSE THEY LIKE IT?
You are naive.