They might prefer iPhones, but the reality is most phones in use worldwide are Android because Apple is too stupid and greedy to price their phones fairly.
Ok but those younger people are a minority, at least 50% of people worldwide, including young people, still use android primarily because it's cheaper and more affordable than iPhones.
It's not really that surprising when you know the whole blue and green bubble thing was targeted at teens and young adults, the two groups feeling the most societal pressure to fit in. Turns out when you make people not owning your devices clear outsiders then people not wanting to be outsiders will buy your products.