I had a culture shock regarding this around a decade ago when my coworker declared (with pride) that his teenage son has his schedule filled up to the brim. I

I had a culture shock regarding this around a decade ago when my coworker declared (with pride) that his teenage son has his schedule filled up to the brim. I recall thinking how to respond. Was that a good thing? What was he so proud of? Two extracurriculars were already a lot back in my school days. To add to the confusion the kids in my neighbourhood don't seem to attend many classes as I see them on the playground. Is this an upper-middle class thing that I'm supposed to participate in now?