Because I was still a kid.
I spent one year abroad (grade 6) and during that year I was sill pretty comfortable with being a kid- playing, not caring about clothes, watching cartoons and and not really paying attention to popular music and trends. Meanwhile my old classmates transformed. Partially i was the youngest in my generation so many got hit by puberty already, but also the place was simply different
I remember coming back and I was eager to meet my friends and I was shocked to see everyone wearing a certain fashion, looking very posh, acting mature... and I was there in shorts and tshirt thinking we'd go play.
I didn't respond well to that i became very self conscious and withdrawn and then I got bullied. I picked up on that too much in return and became a total jerk to everyone until high school finally got me to experience normal and positive interactions with peers