If you watch any 2000s comedy film, or just do a high level skim of 2000s pop culture, that was a very standard trendy attire back then. My parents were into me looking like that in school at the time as well + for photos.

That was a style then. It may not be your thing or mine, but it's not puzzling that someone was caught up in a fashion style of the times.

I am quite sure long sleeve Tee under a band t-shirt will eventually make a come back, given all the nostalgia wave from Gen Z, experiencing their grandfathers teenage years.

It was a preppy frat bro look of the mid-aughts.

It got pretty ridiculous. I had a few people in my classes that would do 4+ layers and show up looking like an artichoke.

https://www.verdalina.com/blogs/journal/the-popped-collar

It was a thing for a while in the early 2000s, mostly as a preppy status symbol. It was pretty much iconic SV founder uniform for a short time.