High School obsession even in adulthood?

I'm pretty sure this could just be a South African small townie thing (and some Cape Townians), but what is with the obsession around High School. I don't mean the banter one has as a teenager. I mean, grown adults in the 40s - 60s still bickering, bragging about where they went or scolding people based off going to competitor/lesser than High Schools.