College students =/= young people
even looking at just 18-24 it's like 1/3 of them and not a representative sample, and grad students are an even tinier group of mostly mid-late 20s
College provides (usually) a built in community and likely even a walkable neighborhood, and many opportunities to meet people that the general working public often lack. Didn't stop apps from becoming popular on campuses, but I feel like it was always destined to be a fad in that context, because the apps suck so much