It’s more that what you wear, if you have a choice in it, can go a long way to establishing your identity to yourself and/or signifying to your peers what you’re into. When I was in school, nobody cared about what you were wearing very much at all, as long as it covered the important bits. If they were going to bully you, they were going to find whatever reason for it, even if you dressed “well”.

Mind, I went to high school twenty-five years ago in Canada, and I don’t think things were as badly stratified as they can be in the US - or the UK. We don’t (or didn’t, anyway) have hard class divides, and even social groups based on interests were flexible. I - a geek - had friends who were sporty, punk, stylish, artsy, etc, and I’m fairly sure I wasn’t an outlier.